[DuncanIdaho]

That would be hard to do and pretty pointless.

Do not forget that mining bitcoins becomes progressively harder with time.

Thus to get any sort of meaningful reviews, they would have to review whole field of graphic cards each time a new one comes out.

Not feasible.

Edit: Ok, so I don't know anything about Bitcoin mining, thanks for clarifications.

[jl6]

No, there is a very simple, well-defined and difficulty-independent metric of Bitcoin mining performance: hashes per second.

[matthew-wegner]

Finding a solution becomes harder with time, but the number of algorithmic checks performed per second is constant (more checks are simply required as difficulty increases).