I find is somewhat surprising you've been directed to use an MR release. How exactly are you supposed to use new AP's on an MR? As far as I'm aware the R650 is only supported on 5.2.
Also, GA is GA, it's released to the public. Sure, an MR is going to have issues fixed, but any GA release shoudl have been based off the previous MR. It's like they are building each GA from the fround up with new code.
Just disappointing really. I keep upgrading as I keep hoping more bugs are fixed than are introduced. So far, not a lot of luck in that regard