I'm going to hop onto a couple of these last posts.
As a Husky and Gas Gas rider, I think they're both great (09 WR 250 and 300, '08 EC250). I wish the Gas Gas was as easy to work on as the Husky, and I wish the Husky was as easy to ride as the Gas Gas. Hmm.
I think that Gas Gas can easily outsell Husqvarna with it's two stroke line. Husqvarna is very well established with it's four strokes (cough, ack). The WR 250 has a faster engine, and the Husky has the big Zoke fork, but I still prefer the Gas Gas if I have to ride fast in the woods. I've said it for years, all you have to do is get some people to ride these bikes and they will sell themselves.
As far as bike sizes go, I just happen to be that target sized rider, 5'10" tall, 155 pounds, so fit has never been an issue for me. But thinking about it, any suspension tech will be happy to shorten your suspension. Unfortunately, it doesn't sound very cost effective to import short suspension, that would likely need a revalve anyway depending on whether the rider was a kid, a woman, or a short fat dude.
On being tall, I feel for LankyDoug, because he probably would have been happier on a Husqvarna. They are tall. The bike still needs a revalve, but at least he wouldn't be cramped. Gas Gas bikes feel like they are "almost full scale" in comparison to a KTM or Husky. Like 7/8ths scale, at least to me. That's what I like about them. For a big guy, that might not be so hot.