If you want to shoot with any RF, then you have to accept the framing compromise. Much same with any gear or system; there are always compromises. OP, in your case it sounds as if you wish to use a M but want to be able to have square frame lines for both the 35/50 FLs and the build quality of the M3. If so, then I recommend either the M2 or M4. I use both models a lot and can recommend either very highly provided you accept the RF compromise.