BFG probably has the best warranty policy of all the different nVidia partners, lifetime warranty and they don't care if you OC either (last I checked). EVGA is pretty good too from what I hear. I actually wanted the BFG part but there was a $30 difference in the 1 day I had it in my cart and the day I bought my new parts......
I'd wait a bit and see what the actual price is on these. They may MSRP for $299 but I'd probably expect $280 or so from the better e-tailers when the NDA is lifted and that could fall even more shortly after with rebates. The OC'd parts are coming in so the original versions are going to fall in price. As someone mentioned, that leaves very little price difference between the original parts and these newer ones, so the only place for them to go is down.
But ya in terms of performance these look great. They're not neutered at all compared to the 640MB GTS, same memory interface, # of pixel pipes, shader units, shader clock, memory and GPU clock, just half as much memory. The rest of the mainstream DX10 parts to be released are all going to be cut down in at least one of the above areas.