Cure 2 is 650 pot, 266 mp vs Overcure Cure 3 550 pot, 200 (199?) mp. That is 2.44 vs 2.75 pot/mp, so if you were gonna use a non-Freecure Cure 2, it would be slightly less efficient for a single target heal than Overcure.
Not gonna go into a debate of how often that might be useful here, just saying.