Agreed, It was easier to manage. Its a few years ago, but i think the original velocity figures were 430 fps versus 485fps for the M with R10 pellets, but where most of the M versions were making little better than 460fps at the club.
The strange one in favour of the M is cocking power was not altered. If you look carefully you can see the lever stem which protrudes out of the base of the cylinder in front of the trigger guard. You will notice it is longer in length. This allowed the cocking effort to be the same...but of course, this all added extra mass.
The 46 and 46M eventually disappeared from the club with the advent of these new PCP pistols. A club charging compressor was purchased to make things easier for everyone which could have been the main reason, but for self contained home shooters, I suppose it is ok.