Flows are a spin dial on the lever. I don't remember what Cinchs are, and I would guess Gnu's are similar to Flow.
Flows are generally just better. Fast isn't the selling point in my opinion, comfort is. The others are still just two strap bindings made heavier to accomadate a "faster" in and out. Flows are faster in and out, average weight, and they are far more comfortable.
Go ahead, drink that kool-aid.
FS: Forum Sauce 142 $200 plus shipping
FS: Flux SE30 $75 plus shipping