Xohm, of course, is rolling out some places; you won't have access till the public launch, though, and I don't think any great detail of launch coverage areas is available.
If they were the same price, I'd obviously go for the N810W, because I like the looks better, and extra connectivity options are cool. But they aren't the same price, so IDK. The WiMAX radio's the only difference, and it shouldn't draw any more power when not in use.
I got mine for $299 + $15 shipping from an ebay seller. It was sealed and came with warranty and all that. I have been using it for past two weeks sans trouble.