Well the Black Edition GTX260 is overclocked from the factory, so if you go that route you can't avoid it. All things considered, however, the 275 would still be a better choice since they both probably cost about the same. You could also look into ATI and check out the 5770 or 5850
Personally, I wouldn't trust that HEC, but that's just my opinion. From the looks of it, it is an active PFC unit with a pair of 25A rails, but I don't put much confidence in their ratings. Their reputation isn't the best, and I just wouldn't chance it.