True, the Mk1 is as good a pistol as the Mk2, except it doesn't had the hold-open on an empty mag and the mags are 9 rounds instead of 10.
The first handgun I owned was an Mk1, and RST-6 to be exact. It had fixed sights, so that meant a little 'Kentucky windage" sometimes, but the groups were always excellent if I did my part.