Fives are good. And I'd almost take any Flow over any Gnu. They aren't adjustable enough and the ankle strap sits too low. Also the toe strap doesn't stay fixed so I found myself having to manually adjust that every time I strapped in. So they aren't even any faster.
I have and currently use 2012 choice, and I agree with this 100%
But I do have to say that it is EASIER to get in to. My bro has fives and takes a little while longer to get in.
Adjusting the toe strap doesnt really take time, more of an annoyance you could easily live without.
Performance wise, I wouldnt be able to tell you. Tried to use the flows but it turns out my bro has tiny feet.