do you mean, 2d10 as in 2-20, or 2d10 as in 1-100? if the latter, the main difference is that instead of rolling in units of 5%, one rolls units of 1%. widens the range of variance, especially if you use the defensive ac roll optional rule in addition.
i'd play it either way. the exact mechanic isn't that important to me. just so long as i know what it is. good roleplaying and having fun are the more important things, i think.
edit: seems like this was the level 22 post. ^^