The may share the "EXACT same keys" as in the all use FATAR TP/9S, but that doesn't mean they'll feel the same. The same keys will feel different depending on the strength of springs used, aftertouch mechanism, chassis, etc.
My Rev2 and OB-6 feel quite different. The Rev2 has noticeably stronger resistance and more consistent action. As a piano player always looking for strong keyboard action, it's really nice. My OB-6 feels great relative to other synths (the Moogs and Korgs I've tried), but a little plastic and weak in comparison to the Rev2 or my MFB Dominion 1, which has by far the nicest keyboard action of any synth I've played (and yes, it's also TP/9S plastics, but the insides make a difference).