Well, the key difference is that odd and even front defenses have completely different responsibilities and personnel needs. Without going into great detail, it is theoretically possible that we'd be worse off in an even front defense than odd front because our personnel may not be able to properly execute the different responsibilities in even front.
WITH ALL THAT SAID, we are a mixed front defense at this juncture under Saban. We may be a base odd front defense, but we play a bunch of even front single-gap looks and even sometimes play split fronts where the strong side is two-gapping like an odd front and the weak side is single-gapping like an even front.