Zen Crescendo or 5a...will they work in my room?

I'm looking for some thoughts here...

My dedicated listening room is 20'x 15'x 8' with the back wall behind the listening chair 4' high and opening into the kitchen area. The supported floor is wood and there is a 2' high crawl space underneath. The speakers can out from the short wall as much as need be, and proper treatment of the room will be done.

My very short list has come down to the Acoustic Zen Crescendo, and the Vandersteen 5a non-carbon. I have listened to both and could be very happy with either. Since I am a fan of tubes, I suppose the Crescendo has nosed perhaps ahead in the race, due to the fact that they seem to enjoy being paired with them. But I'm not dismissing the fact that the Vandy's woofers are self-powered, leaving the rest of the spectrum to be powered by perhaps a 100w tube amp.

Does anyone see an issue with my room dimensions when it comes to either of these speakers? Will the crawl space below lessen the chances of getting excellent bass response from either speaker?

I'd have more of an idea to what would work in my environment, but this is a new house and I've yet to put a system in there.

TIA...