I've owned DM and currently own Getaway. As others have said they are pretty similar IMO. DM has some pretty cool multiball action. I havent had Getaway very long, only a couple months. I like it though.....alot. The simplicity of it is nice. I only have two games TSPP and Getaway and they contrast each other nicely. I would say the PF looks prettier on DM and blue LEDs in the GI look nice IMO. Getaway can give you a more "adrenalin" feel I think.
In the end, its all personal preference. If you've tired of Getaway go for the DM. I dont think you'll be disappointed per se. The only thing I'd caution against is if your Getaway is in really nice shape (cabinet has no fade) then the chance of you finding another in that great of shape is probably not so great. DM is probably easier to find in overall better shape.