I have a Mark II 678 Target model and love it. I have tens of thousands of rounds through it with no issues. I am an Basic Pistol Instructor and CPL Instructor and our club bought several Mark III for use in First Shot classes and other instruction. They have been less reliable (picky on which ammunition they like) and much more difficult to reassemble after cleaning. I believe this is due to the extra links in the magazine disconnect.
That said, If I was buying a .22lr for a personal plinker or inexpensive training, I would not hesitate to get either a Mark II or III.
The only .22 I have seen that consistently has issues is the Sig Mosquito. There may be exceptions and i love to shoot it, but it seems to have Failure to feed issues no matter how you clean and lube it, and no matter which ammo you use.
Every one should have a rimfire pistol, great practice and you can shoot all day for less than a box of centerfire ammo.
That said, If I was buying a .22lr for a personal plinker or inexpensive training, I would not hesitate to get either a Mark II or III.
The only .22 I have seen that consistently has issues is the Sig Mosquito. There may be exceptions and i love to shoot it, but it seems to have Failure to feed issues no matter how you clean and lube it, and no matter which ammo you use.
Every one should have a rimfire pistol, great practice and you can shoot all day for less than a box of centerfire ammo.