A few thoughts, if I may. Me, also a previous E39 M5 owner, as well as an E28 M5 and lots of others... and current CT5V-BW owner.
BMW makes a great car. I strongly disagree with whoever said that this new fat pig won't survive a day at the track - I'm sure it will. They are designed and built for that kind of abuse. I've driven the F90 M5 and it is an awesome thing. I think it's too expensive though, and so the last 5 series I bought was a 550, which is very close to an M5 but like $50K cheaper. But not once did I feel like I was driving a "real" M car either...
That said, very few people are going to take their new $130K car to the track. Or their $30K car. We are the outliers, not them. Me personally, I believe that these cars are built for that purpose, and to not drive them at least once on the track is a sacrilege. But I get that it's not for everyone. And it's dangerous, and expensive, yada, yada, yada.
I think the reason that most BMW M owners have not gravitated to the BW line is, aside from availability, that there is just still a lot of baggage on the GM product and Cadillac especially. I confess that I initially discounted the BW because I knew I wouldn't be able to get one, and the OG CTS-V was just so hideous inside that I couldn't believe that it would get much better. Fortunately I was wrong on both counts.