Advantages and Disadvantages of SM

[munin]

Here's my list (+ = Pro, – = Con, / = Situational):

Higher SM
+ Buy ST, HP, Arm ST, Lifting ST, Striking ST at reduced cost (SM +1 or more, p. B15, 16, 40, 66, 89)
+ Immune to Constriction Attack (relative SM +1 or more, p. B43)
+ Easier to intimidate, harder to be intimidated (p. B202)
+ Easier to pin, harder to be pinned (p. B370)
+ Can squeeze torso (relative SM +1 or more, p. B371)
+ Increased reach (SM +1 or more, p. B402)
+ Easier to hit when you grapple (p. B402)
+ Can trample/overrun (relative SM +2 or more, p. B404, 432)
+ Longer poison delay (p. B438)
+ Eat less frequently (p. BIO63)
+ Larger weapons do more damage (p. DF1:27)
+ "Realistic" larger creatures eat proportionately less amounts of food† (p. S149)
– Easier to be hit (p. B19)
– Easier to be noticed (p. B19) by Vision (p. B358) or Vibration Sense (p. B96)
– Vulnerable to Parasitic Possession (relative SM +1 or more, p. B76)
– Harder to be camouflaged (SM +1 or more, p. B183)
– More damage from extreme pressure (SM +2 or more, p. B435)
– Eat more food† (pp. BIO62-63)
– Require more space and life support (p. BIO63)
– Larger equipment costs more and weighs more (p. BIO63, p. DF1:28, p. HT10, p. P50, p. UT16)
/ Increases the size of a Jumper Tunnel (p. B64) or Permeation Tunnel (p. B75)
/ Costlier to be affected with Regular spells (SM +1 or more, p. B239)
/ More likely to block line of sight (p. B389)
/ Attack counts as Large-Area Injury* (relative SM +7 or more, p. B400)

In addition, higher SM can be justification for some traits, but you'd have to actually pay for the traits themselves:

+ "Realistic" larger creatures have higher ST (p. BIO64)
+ "Realistic" larger creatures have longer lifespans (p. S159)
+ "Realistic" larger creatures might more easily see low wavelengths (p. S162)
– "Realistic" larger creatures might have a penalty to their sense of touch (p. S162)
/ "Realistic" larger creatures have higher weight (FEATURE, p. BIO64)

Lower SM
+ Harder to be hit (p. B19)
+ Harder to be noticed (p. B19) by Vision (p. B358) or Vibration Sense (p. B96)
+ Immune to Parasitic Possession (relative SM +0 or less, p. B76)
+ Undetectable by Radar (SM -1 or less, p. B81)
+ Simpler to grapple a prone, kneeling, or sitting opponent (relative SM -2 or less, p. B370)
+ Eat less food† (pp. BIO62-63)
+ Require less space and life support (p. BIO62)
+ Smaller equipment costs less and weighs less (p. DF3:8, p. HT10, p. UT16)
+ Attacks require Vision roll to notice (OPTIONAL, relative SM -10 or less, p. P76)
+ Easier to target armor chinks (OPTIONAL, p. P76)
+ Easier to get inside armor/body (OPTIONAL, relative SM -13/19 or less, p. P76)
– Vulnerable to Constriction Attack (relative SM +0 or less, p. B43)
– Harder to intimidate, easier to be intimidated (p. B202)
– Harder to pin, easier to be pinned (p. B370)
– Shorter poison delay (p. B438)
– Eat more frequently (p. BIO63)
– Smaller armor provides less DR, smaller weapons do less damage (p. DF3:8)
– Impossible to target out-of-reach hit locations (OPTIONAL, p. P76)
– "Realistic" smaller creatures eat proportionately greater amounts of food† (p. S149)
/ Reduces the size of a Jumper Tunnel (p. B64) or Permeation Tunnel (p. B75)
/ Less likely to block line of sight (p. B389)

In addition, lower SM can be justification for some traits, but you'd have to actually pay for the traits themselves:

+ "Realistic" smaller creatures can carry heavier proportional loads (p. F51)
+ "Realistic" smaller creatures might have a bonus to their sense of touch (p. S162)
– "Realistic" smaller creatures have lower ST (p. BIO63)
– "Realistic" smaller creatures have lower IQ (p. BIO63)
– "Realistic" smaller creatures have shorter lifespans (p. S159)
/ "Realistic" smaller creatures have lower weight (FEATURE, p. BIO63)

* So a human punching a mouse would be inflicting Large-Area Injury (STBY, mouse). I think all that means is that you average the mouse's DR (which is likely zero anyway).
† The notes about food consumption might be confusing. Larger creatures eat more food, but the amount of food is smaller proportionate to their weight. Smaller creatures eat less food, but the amount of food is larger proportionate to their weight. However, if you follow the rules from Bio-Tech (pp. 63-64), which provides detailed numbers, you'll find that the weight of food consumed is roughly proportionate to BL at most sizes.

[sir_pudding]

There's still the logical effects of size reach and leverage. FREX a 3 in. mouse that can lift a car vs. the 50 foot giant that can do the same.

Originally Posted by munin

+ Larger weapons do more damage (p. DF1:27)
– Larger equipment costs more and weighs more (p. BIO63, p. DF1:28,
+ Smaller equipment costs less and weighs less (p. DF3:8, p. HT10, p. UT16)
– Smaller armor provides less DR, smaller weapons do less damage (p. DF3:8)

You should probably reference the rules in LTC2 here instead of or in addition to DF3.