I would liken it more to the OSX PPC > Intel transition than between OSX > iOS, though both did involve porting a whole operating system to a new processor arch

I would liken it more to the OSX PPC > Intel transition than between OSX > iOS, though both did involve porting a whole operating system to a new processor architecture. In the case of iOS, Apple had a fresh start so there was no need for inter-compatibility between mobile and desktop apps, so no transition layer was ever created. For PPC > Intel, they created Rosetta (an emulation layer that allowed the older apps to run) in order to smooth the transition, and make it somewhat transparent to the user. This was a win by all measures, users got a completely different underlying system that was faster and more power efficient, and they never had to think about it; that's not to say it wasn't slow, but it wasn't something you had to think about. Microsoft really should have taken the route Apple did, it's the same OS on new hardware that needs an emulation layer to run old apps- and that's alright until there's native builds of the most common suite. The fact that it was barely ever mentioned in Apple's transition says that it worked, and the constant confusion RT causes shows that Microsofts didn't.