We had a really cool Belgian WB mare at our barn for quite some time, and I"ve seen a lot at shows. (usually jumpers) It's the same as every breed though, there are some great ones, some not so great. There's a market for any good quality horse that's well trained, east coast or anywhere. Any quality WB bred to a compatable and quality pony could produce a stellar foal. But it depends on what you're wanting out of the foal, the parent's conformation/attitude, etc. Crossing a pony with anything can be tricky IMO. A 14.3 horse has very little resale value and a hot jumper pony is just hard to sell if not more so. If I was breeding ponies I'd be looking at child friendly hunters. If I was looking for something to breed to my pony I'd wouldn't look at a specific breed, I'd be looking at a bunch of individual WB stallions that would be the most compatible with my mare.