I was frustrated by my 642 for a long time. I eventually put larger, Pachmayr Compac grips on it which cover the backstrap. I also decided I wasn’t going to try to shoot this gun past 7 yards, and my accuracy goal was to consistently put 15 rounds on a 8-1/2 by 11” sheet of paper. Also, because the sights are so small, I don’t expect to actually be able to use them in a self-defense situation, so I always tape over the rear sight when I shoot his gun, and aim by aligning the muzzle.
Even getting to this level of proficiency – 15 rounds on a standard sheet of paper at 7 yards without a sight picture - took a while. For me, it wasn’t fun or satisfying, and as a direct result I bought an SP101 with a 3” barrel. The main advantages of the SP101 are better ballistics from the longer barrel, better sights and it’s easier to grip properly. Yes, it’s longer and heavier than the 642, but overall, the SP101 was a better package for me.
Having said that, I eventually came to consider the Glock 26 and 19 as my primary handguns, since I shoot both of these better than the SP101 and they hold more ammo. The Glocks aren’t slim, but for me they conceal better than any revolver.