Wow, good points from OP and B-1.
I agree with B-1, I think 601M's are equal in appearance appeal to 343M, I just personally like the 343M's a bit better since they were the launch wheel for the F10 M5.
I don't know if anyone here has ever picked up a 343M with a tire on it, but jeezus is it heavy. The 343M's may be forged but they aren't exactly light either. The weight of the 601M's makes it a little worse, it's true, but as other have pointed out you are not going to notice a 23lbs weight difference on the street, and maybe if you were Randy Pobst or Chris Harris, you'd notice the difference on the track.
The last thing I will say, again which others have pointed out already, is the longevity and durability of a cast wheel, especially on M cars. I don't know the long history of every single wheel ever specifically designed for an M car, but I'd guess that the majority of them were cast wheels. I have only known a handful of people who actually cracked their stock OEM Cast M wheel, and in 99% of those cases, they hit an extremely bad pothole extremely hard. So just avoid potholes and you'll be fine with the 601M's.
