The OG M2 missed the B58 boat because BMW was going to be putting a factory tuned B58 in the M240 and the M2 would need even more power than the M240 and BMW was not able to verify/certify the track reliability of the B58 in a higher performance chassis yet. I believe the biggest concerns being oiling pressure under high Gs and the liquid/air intercooler with additional power.
As an M235 owner for over 4 years, I absolutely love the 2 series chassis and have been very happy with the car and the differences modifications make. I absolutely want an M2. However, I'm the odd ball because I want the OG M2 N55, not the M2C with the S55. With the M2C you absolutely get a faster car with better brakes and better seats. What I like about the OG M2 is its running costs and long-term reliability. It does not use the larger brakes, rotors, and more expensive brake pads or the far more complex motor. The N55 is very simple compared to the S55. With the M2C, you really do get the cost of "M" ownership with the brakes and motor as it's a true M car. The spun hub issue, while rare, is also very scary and expensive if it were to happen. The S55s also have a history of the intercooler leaking coolant straight into the motor. Yikes.
The N55 in my M235 has been great. It's fairly easy to work on for a BMW motor, the intercooling is simple and easy to upgrade, parts relatively cheap compared to something like the S55, and it was the last N55 of generation so most of the issues were either addressed and/or are very well understood.
Lastly, I don't recall much argument with the 1M and its lack of a true M motor (simply a tuned and slightly beefed up N54)
The OG M2 destroys it in every contest, as it should.