Reverting back to Windows 8.1 Pro to enjoy my Windows applications/games and not to be constantly frustrated with this upgrade/activation issues, to put it very MILD!
I'll sit out the ride with Win8.1 atm, untill issues are ironed out a bit more!
Cheer
W8.1 ran pretty nice on my MP 5,1 but I often had little issues. Finally I got tired of the occasional fiddling and bought an HP Z230 for about the price of an upscale mini. What a wonderful improvement. All the Windows stuff works great, choice of equipment is enormous and I've got more USB3 ports than I can possibly use.
I upgraded to W10 last week. There is a bunch of unfinished business there such as Photos and Music but it runs really great. No improvement in Geekbench scores but the 3.6GHz i7 quad seems to run every bit as fast as my 3.45GHz six-core MP. I've got Bitlocker working on all drives and an actual, working built-in USB3 card reader. Love my Mac Pro but I am also really glad to be back to a genuine Windows PC.