I pretty much agree with you. I would never buy a car because of 1/10, I will add that the M3 is way more predictable and stable than the 1M. The 1M is much more humbling, while the M3 really builds confidence with it's driver. Even though the 1M is not quite as fast as the M3 it 'feels' faster, more dangerous. I guess for me, when I had the M3, I could hit triple digit speeds and I would almost have to look at the cluster to confirm how fast I was going, with the 1M, the car lets you know you are moving. It's definitely more work to keep the car controlled at the limits than the M3.
BTW, my Ideal car would be an E30 M3 body, an E46 S54 engine(new lighter version as its heavier than an S65), add a few air bags, ABS, DSC to meet today's safety standards. No doubt BMW could build this car with current lighter materials they are using and keep the weight much closer to the original E30 than the 1M. But they are not building cars specifically for Pavel Metak.
Hell, if they re-re-released the E30 with the 4cylinder I would be first in line!