[Varyon]

As I understand it, by RAW, the size of the attacker doesn't matter, only the range and size of the target coming into play.

At first, it seems like relative SM should matter, but consider a few scenarios. We've got two SM-6 (0.2 yards tall) characters, two SM+0 (2 yards tall) characters, and two SM+6 (20 yards tall) characters fighting. When equal-SM characters are matched up, things work out decently well. At 10xheight distance from each other, each is dealing with the same penalty - the SM-6 guys are 2 yards (+0) apart, the SM+0 guys are 20 yards (-6) apart, and the SM+6 guys are 200 yards (-12) apart, so when you add in the target's SM, everyone is looking at a -6 to hit. There is the issue that, going off of RAW, the SM+6 guys can effectively get a bonus by getting really close (at 10% height - 2 yards - they have a total +6 to hit) while the SM-6 guys are at the same penalty as at 10xheight anywhere closer (as you can't get a bonus for being closer than 2 yards), but that's easy to fix - set the "no bonus when closer" point to 1xheight (rounding up to nearest SSR). That means the SM-6 guys are at +0 when 0.2 yards or closer, while the SM+6 guys are at +0 when at 20 yards or closer.

Uneven matchups work out as well. Looking at the most extreme, we've got SM-6 vs SM+6. Assuming 10x[attacker's height] distance, the small guy is at +6 (+0 for a Range of 2 yards, +6 for an SM+6 target) to his attack roll, while the big guy would be at -18 (-12 for a Range of 200 yards, -6 for an SM -6 target). This still makes sense - if we were to scale each attacker to SM+0, and scale the distance and target size the same way, the SM-6 character attacking an SM+6 one at 2 yards becomes an SM+0 character attacking an SM+12 one at 20 yards (total is still +6), while the opposite case becomes an SM+0 character attacking an SM-12 one at 20 yards (total is still -18).