I like the idea of the mag release behind the trigger guard, but I have the Ranch Products extended heel clip release on my Mk.II and I can release the mag with my little finger very quick and easily on Mk.II. 

I seem to remember there were a couple features I didn't like as much on the Mk.III but I don't recall now what they were.  I think they might have a magazine disconnect, which doesn't bother me at all.

I'd like a stainless pistol but I've never pulled the trigger on that.  Because I have the blued 5.5" bull barrel, which I think is a beautiful pistol, I'd kind of like the plain 4" standard model in stainless, fixed sights and all.  But since I don't shoot a lot of .22, two .22 pistols would be the maximum number I'd want, and the 22/45 is also interesting to me.  I like it because it has the same grip angle as the 1911.  I'd like to get the model with removable stocks that lets you use any 1911 stocks on it rather than the version with molded-in "stocks."  The downside to the 22/45 is that I'd need a new set of magazines.  One of these days I'll have to decide.