DMVPN Design using FrontDoor VRF

This posts looks more to analyze few design questions and good information on how to complete a successful DMVPN implementation, other than a focus on the configuration. And last but not least, to start a conversation and hear more about what would you do in cases like this (There are many ways to skin a cat!!) A short background on what got me to this: I have been most of my Professional career focused on UC and Collaboration technologies until not too long ago that I decided that I wanted to get involved with Security and Networks again. At this point my focus is to be able to maintain a good deal of knowledge on the technologies that cover all Cisco Security suite, but UC is still a great part on what I do daily at my current position.