A couple of things I want to comment on here...
1) This was said several times, but again people continue to miss the point of the OP, THIS IS NOT REALLY AN M3 SEDAN, IT IS A MULE
2) On the HPFP concerns, frankly I would ignore it. No matter if you have a blown I6, or a NA V8, any car is going to have issues. That is why BMW has many of those things called engineers to figure it out when there are problems and fix it.
3) There is still a lot of speculation about what engine is under the hood. IDK ig the OP has true inside info, or what. If we trust the guys at M division to take a normal 3er and turn it into an absolute beast, why not trust them to take whatever engine they please and do the same thing?
No offense, but I think that alot of us speculating (myself included) forget that the guys working on the motors, turbos, and M3 project in general are professionals. This IS what they do for a living.