I have used the 35 Cron IV and the 50 Cron V with the M9.
The 35 Cron IV is a dream on the M9. I absolutely love it. However, the 50 front focuses like it's no one's business. Funny thing is that it tests out fine with most of my film cameras (M6, MP, M7). Not sure what the issue is but my copy is worthless on the M9. My 75 Cron is even worse with the M9, as it front focuses with all my film cameras (needs adjusted so it really has nothing to do with the M9).
The biggest problem that I have found is that many of my lenses will not focus correctly with my M9; some back focus, some front focus. If you could, I'd recommend testing the lenses you want to use with the camera. I emailed Golden Touch about adjusting the 75 Cron and she wouldn't do it - she had recommended sending my lens along with the M9. NO WAY I am sending 40k worth of glass along with the M9 to NJ!
I consider myself blessed that my 24 Lux, 35 Cron, 35 Lux ASPH and Noct all focus fine with my particular M9.
Funny but I don't really miss many of those other lenses. Consider my view on the world simplified.