From what I've read, the gto2 always unlocks to 16 pipes successfully, but the OC'ability varies from card to card. But even a "bad" gto2 will still hit at least 500 on the core, which is a 100mhz overclock. The gto2 also comes with 1.6ns mem, rated at 1200mhz ddr, and it usually can run at least 1100mhz stable.
The problem is that all the gto2's are either sold out or overpriced. $250 or more is not a good deal on it. I missed the opportunity to snag one up at $199, so instead I ordered a Connect3d x800gto - many people have successfully unlocked those as well, but some dont unlock, so it's not guaranteed. The c3d gto uses the r423 core (as opposed to the r480 on the gto2) which is the same as a x800xt, not the x850xt. It also has 2ns mem rated at 1000mhz ddr, but with decent cooling many people are getting past 500mhz on the core and past 1000mhz on mem, so for $179 from monarchcomputer it has the potential to unlock and perform as fast or almost as fast as an unlocked gto2.
From what I know, only the connect3d gto has a chance of being unlocked, so get that one if you cant get a gto2.