Cstooner,
Sadly, I'd have to say that a great system won't necessarily sound great in any decent room. Far from it - on at least on two different levels, IMO.
First, I believe that the room issues below 100ish hz are, in almost all cases, best addressed with room correction software, (but I also know that many here will disagree). I've heard many excellent systems transformed by DRC software, even in excellent rooms as the inevitable low frequency room induced FR issues are cleaned up. Check that out for yourself to decide where you end up on the issue.
The other issue is simply room volume (cubic feet). Any given Speaker model generally sounds much better in a room of a given volume. The big MBLs (to cite one example) can sound great in a huge room, but I'd never want to listen to that speaker system in a small to medium sized space.
I hope you can recreate the outstanding experience you heard on audition with the same system in your own room. I like stories with happy endings. I just wouldn't be completely confident until I actually heard the results.
Best of luck in the effort.