Daring to ask the what does SM do question.

[Flyndaran]

I hope this doesn't end up locked on its first page, but I'm curious how people feel about size modifiers.

What pluses and minuses does larger and smaller than campaign average size give? In R.A.W., reality based on your opinion, and in preferred play style fiction?

Let's keep this cold and emotionless, please.
I hope this doesn't sound trolling or asking too volatile of a question.

[gilbertocarlos]

http://ottgaming.grimoire.ca/Borderlands/Size_Modifier

[Anthony]

Well:

Originally Posted by Kromm

High SM is good because it . . .

• allows you to hurdle larger objects as a free action (p. B352).
• enables trampling (p. B404) and overruns (p. B432).
• entitles you to buy cheaper ST (p. B15), Arm ST (p. B40), Lifting ST (p. B65), Striking ST (p. B88), and HP (p. B16).
• gives you extra reach in melee combat (p. B402) and lets you fight at a height advantage (p. B403).
• grants bonus DX and ST when grappling, whatever grappling rules you prefer.
• makes you more costly to affect with harmful Regular spells (p. B239).
• means you have no penalty to wield higher-SM melee weapons that enjoy improved damage, whichever weapon-scaling rules you prefer.
• renders you more intimidating and less likely to be intimidated (p. B202), and allows you to shrug off the fear effect of being charged (p. B397).
• slows the effects of poison (p. B438).

High SM is bad because it . . .

• amplifies the effects of being crushed by high pressure (p. B435).
• causes you to be hit by more fragments from explosions (p. B415).
• leaves you more susceptible to high-RoF attacks when motionless (p. B409).
• makes you easier to hit (p. B19), whatever version of the rules you prefer.
• makes you more costly to affect with helpful Regular spells (p. B239).
• means you must pay more to eat, if using the optional rules for that.
• raises the cost and weight of your gear (p. B20).
• renders you easier to see (p. B19).

There are also the things on the Borderlands page, which are slightly different but largely consistent. The main issue is 'does this add up to zero'. Running through them:
Good-1, Good-2, and Good-4 can be granted by Stretching-1 [6]. You can also achieve the same effects, in a more expensive way, by taking Long Legs and Long Arms; I have never seen anyone actually do so. Note that the 'combat at different levels' part of SM is not clearly stated in the rules, and in practice is confusing, because if my feet are 3' lower than his, and my head is 3' higher, am I 3' above him, 3' below him, or something else?
Good-3 depends your ST; if you don't want high ST, it's totally useless. In practice, ST beyond 20 hits pretty serious diminishing returns, so we'll value this at [10].
Good-5 is +1 to hit with your choice of wresting type skills (standard single-skill Talent), and also +1 to Lifting ST, only for grappling. It doesn't grant any of the other benefits of high skill or ST, so call it [3].
There is no easy way to price Good-6, but it's probably balanced by Bad-5.
Good-7 is of extremely marginal value, as scaled weapons aren't very good, and is traditionally granted by a 1/level perk, so call it [1].
Good-8 is a limited Fearlessness, plus a 'bonus to skill rolls' talent, so [3].
Good-9 is almost never relevant, call it a Perk [1]
Total of positive effects: 24 points. Now for negative effects:
Bad-1 is almost never relevant; call it a Quirk [1]
Bad-2 and Bad-3 are basically subsets of Bad-4.
Bad-4 is an effect that cannot be directly bought in GURPS, but in effect it's like granting everyone half a level of deceptive attack on you (-1 to all active defenses is ~30 points) and it applies even when active defenses wouldn't, so call it [-20].
Bad-6 is roughly equivalent to half a level of Increased Life Support (Massive), so call it [-5]
Bad-7, for our 20 ST example (as above), is equivalent to losing 6 points of Lifting ST, only for equipment (call that -50%, so [-9]) and a level of wealth, only for personal gear (less significant, call that [-3]). IMO Lifting ST is underpriced (I'd swap its price with Striking ST), but not a big issue.
Bad-8 is an antitalent with stealth, camouflage, shadowing, sleight of hand, etc; fairly standard [-5].
Total of negative effects: -42

If instead we look at SM -1, we'll do a comparison at ST 10, and all the signs on effects are flipped, and -6 lifting ST becomes +4 lifting ST. This gives a total of -14 in disadvantages, 39 in advantages.

[dataweaver]

Good-3 definitely depends on your ST; value it at 10% of the points you've spent on ST (including all of its variations). Conversely, reducing your SM below 0 doesn't increase the cost of ST; so you should drop the cost of Good-3 rather than flipping it.

This all assumes, of course, that the component costs are additive. Since GURPS tends to make that assumption, I'll roll with it, noting only that the cumulative costs probably bear little resemblance to the actual utility of SM +1 and -1, respectively (which is probably a moot point, because GURPS point costs aren't utility-based anyway).

[David Johnston2]

Originally Posted by dataweaver

This all assumes, of course, that the component costs are additive. Since GURPS tends to make that assumption, I'll roll with it, noting only that the cumulative costs probably bear little resemblance to the actual utility of SM +1 and -1, respectively (which is probably a moot point, because GURPS point costs aren't utility-based anyway).

As the person who posted that thread, I agree, but GURPS also really doesn't make the assumption that component costs are additive. Usually the full thing costs less than the sum of its parts.

[Flyndaran]

Originally Posted by David Johnston2

As the person who posted that thread, I agree, but GURPS also really doesn't make the assumption that component costs are additive. Usually the full thing costs less than the sum of its parts.

However you come to a number, it still works to compare the negative SMs to.

[Anthony]

Originally Posted by dataweaver

Since GURPS tends to make that assumption, I'll roll with it, noting only that the cumulative costs probably bear little resemblance to the actual utility of SM +1 and -1, respectively.

Eh, it's in line with my overall experience; while I'd probably change the prices of a lots of parts, overall +1 SM as a -20 point disad and -1 SM as a 20 point advantage seems pretty fair; increased SM sucks.

Or you can use expanded wound size modifiers, and turn SM into a legit 0-point feature ;).

[dataweaver]

Admittedly, I'm biased on this point; but to me, assigning point costs to something is more of an art than a science. There are some rules of thumb, but no hard rules. For example: if ability A costs X points and ability B costs Y points, then combined ability A + B shouldn't cost more than X + Y points (unless there's some sort of synergistic effect whereby the whole is greater than the sum of its parts.

In this context, the rule of thumb that I generally go with is that if a given trait has substantial benefits and substantial drawbacks, it should cost zero points unless you can provide a compelling argument why the benefits outweigh the drawbacks or vice versa; and comparing the relative point totals of benefits vs. drawbacks doesn't make for a compelling argument in and of itself.

What does make for a compelling argument? Depends; that's why it's an art and not a science.

[Anthony]

Originally Posted by dataweaver

In this context, the rule of thumb that I generally go with is that if a given trait has substantial benefits and substantial drawbacks, it should cost zero points unless you can provide a compelling argument why the benefits outweigh the drawbacks or vice versa.

In my experience, +SM provides a bunch of fairly irrelevant benefits with substantial drawbacks, and -SM provides a bunch of substantial benefits with almost totally irrelevant drawbacks (the mismatch has to do with who takes each type of build; -SM tends to taken by characters who aren't planning on doing any of the things -SM makes you bad at. It's a lot harder to avoid the penalties of +SM).

[Flyndaran]

I would really like for some really tall strong and short people to give their input. Which problems are avoidable and which aren't, for example.