Size has a considerable effect on melee damage. Smaller races are noticeably weaker damage-wise. It doesn't make certain race-class combos unplayable but people are very reticent to make sprite swashes or rogues for ex. when they know they can roll a human, get hasted and have higher max con and str along with higher base damage due to size.
Size also factors into certain things like bashing and dodging. Smaller races are more likely to "fail" bashes and trips on larger races, while larger races are more likely to "miss" smaller races the bigger their differences.
Between every other race, differences in max dex have no effect on number of attacks. The only things in question are their profiency in 2nd/3rd/4th attack, the weapon's speed, and modifiers to weapon speed (such as haste, fury, specialize).
Most 4th-attack-capable weapons cap at 5 hits I think w/ things like haste and specialize, but a few extremely fast weapons are capable of getting another attack.
I think perhaps it used to be that lightning dex was equal to another attack... but I don't think that's true anymore. A hasted hellion w/ lightning dex wielding a great-axe for example will never get 3 hits even though he normally gets 2, because the haste doesn't mod the weapon speed far enough.
|