The MAS does suck big A. Apple really got retarded on us with like twelve "stores" for which to find/purchase digital content. One has to ask themselves, "Should I get this [random digital thingy] on the iTunes Store, the Apple Online Store App, or the Mac App Store?" So stupid.
But yeah, how did you get the old school software update back? I used Pacifist to simultaneously run AirPort Utility 6.0 and 5.6.6.6.6. or whatever it was, and life is sweet. Note that I cannot get Back to My Mac to work on ML DP3 w/o using AirPort Utility 6.0.