"I cannot find a dealer/person who will let me demo a pair of Belles."
That's a real drag. It's a long shot, but perhaps the Belles company itself would allow such an audition. In order to find a willing dealer, you'd probably have to convince him or her that you were basically ready to purchase ("pull the trigger") on whichever of the two models would win. It might be considerably less appealing to the dealer if she or he thought you were just tire kicking. Another thing you could try is to see if any of your audio friends own Belles monoblocks, and are willing to allow you to demo them. The only other option probably would be to purchase the Belles, do the test and then resell whichever loses--which seems completely absurd to me.
Reviews and testimonials are nice, and I even posted an Audiogon review of the Odyssey Stratos Extremes, but there's no substitute for one's OWN ears. Good luck.
-Bill