From what I've seen from other around here, when comparing the EP350 to subs offered by HSU and SVS, most feel the other two are a little cheaper for the same performance. They also sound a little different from what I've read but never heard them myself.
I believe opinions have changed when talking about the EP500 and EP600. For the size room you are talking about here, I'm sure many here will suggest a sub other than axiom.
Don't be fooled though, I think the EP350 is a fine sub. Not sure about their smaller subs though.