M0 is a great engine as well. One big change on the M1 was moving the VANOS to the front of the engine which will improve serviceability. My wife has a 2018 340i and I've got a 2019 540i so I can look if the 2019 at least is an M1 by comparing them.
A friend is making ~500whp on a pure stage 1 turbo M0 so I'd say they're fairly reliable, but we'll see in a year if I continue.to say that haha
