Actually, I believe that the real difference between the "early" model 15-22's and the current production guns is the older guns don't have a flash hider while the new guns do. I got mine several years ago just after the 12-22 was introduced and even after 2,000 rounds, I have never had an issue. There may be a few other minor differences but I don't know of anyone with the solid barrel design (no flash hider) who's had any problems with the gun. Also, there are now several different options available in the the 15-22 line while the original model was one style/size/color fit's all.
"... Americans... we want a safe home, to keep the money we make and shoot bad guys." -- Denny Crane