I use both Aperture and MediaPro, and I would say that migrating from Ap to MP, while possible, would be pointless. MP is not designed to handle non-destructive editing, and it has no concept of Stacks. If you're using Ap purely as a DAM then it could work, but frankly MP is even more neglected that Ap. PhaseOne have cloned some of MP into CaptureOne, to the point that it no longer makes any sense to pretend that MP is "integrated into a CaptureOne workflow", and have invested zilch in MP more or less since they bought it. Oh, I forgot, they did make the GUI uglier. Kudos for that.
I'm waiting to see where Apple is going. I still find Aperture's DAM tools the best in the market, and the RAW conversion has never really received the praise it deserves. For the cameras I use, I've never found anything better, and I've tried them all. Repeatedly.