The m frame and the m2 frame have a similar nose pieces. The way I filled in the space and smoothed it out will work the same. The distance will be a teeny tiny bit different but the process is the same.
Just a follow up on the M2 XL frame and the Oakley SI URx Carrier Prescription Inserts. The nosepiece snaps into the M2 XL frame without any modifications to the nosepiece. It clicks right into place. I am having the frame filled with my prescription and will report back with the results.