All I can say is that with the old EP350 a number of people on the board would quietly observe that there were other good sub vendors in the price range that might also be worth looking at. With the EP350v3 we don't seem to do that any more.
Between EP350 and EP500 it's primarily a function of room size, how loud you want to plan, and how much money you have
Seriously, even in a small room the EP500 would be "better", but as the room gets larger and/or you want to play louder the extra power helps and the DSP gives you a more intelligent limiter so that if you do push past the sub's limits you just get volume compression not that awful "grunk" sound.
How big is your room again ?
