Again, the mag release change on the MK III was unnecessary on a .22 target/plinking pistol. The heel mag release is secure, and makes sure the mags are fully seated. I really like my MK II era 22/45, but have to take the time to make sure the mags are fully inserted, and I hear an almost inaudable little click or I will have failures to strip the second round from the magazine. It always causes me a little concern as I carry the 22/45 as a woods gun sometimes, so I take the extra time to make sure it is fully inserted. I shouldn't have to do that.
The MK III is too much of a compromise when used MK II's and new Buckmarks are available.