Yeah, I have been dealing with the same decisions... I have an EP500, and probably need a little bit more woofage for my 3500 ^3ft leaky room. I have been contemplating returning it for an EP600; there's more power, with slightly better extension. However, it doesn't have the same WAF.

Two co-located EP500's will probably be my choice, paying a little bit more $$$. However, this probably won't happen for a while, until I landscape my barren backyard.