For the price you paid for your Mk4's no, do not replace them, the Badger rings and bases are excellent, on par with the Leupold Mk4's, but I would not say they are much better if at all, (Certainly not worth replacing your Mk4's). Both setups are excellent. I still use Mk4's on most my stuff, I just wish they would offer a 15 or 20 (15 preferred) MOA on their Mk4 single piece bases.
MEL