I'm the OP and I have both. I love, love, love the way the BuckMark feels (grips, balance, trigger, mag loading) and shoots - gosh it is dead on accurate.
MyMK III is brand new and it needs another few hundred rounds thru it. It has a harder plastic grip. (The thin grip smaller for my 2...
Don't bore sight in a rifle on a bench that points right at the FRONT DOOR. As soon as I walked in and saw that I aimed at me, I ducked and rolled - thinking it was loaded!
No apology, no change of direction. They kept right at it while the next 5 customers walked in.