I can only offer personal opinion of whats happening in my crappy room with my EP500. Just before reading this I mentioned a few things in the following post.
Treated Rooms

I've never had a 350 to compare so all I can say is that a problem room is still a problem room for the 500 but it's still the best sub I have ever owned or heard, despite the room.

With great power comes Awesome irresponsibility.