Since you have already talked the Dr. Hsu, take the time to talk to the folks at SVS (very similar Customer treatment to Axiom).

I'll echo the sentiment of a little extra LFE is usually a good thing. You can always turn the sub down. It is impossible to turn it up beyond what it provides.

With that in mind, think 2-3 years down the road. Will you be in a larger room that requires the extra LFE? If so, a few extra $$ now can save some serious $$ later.