I have both, a Model 10-6 and a Model 15-2. I can shoot about the same size group at 30ft. with both, but I got to say I like the model 15 a little better. Can't go wrong either way.
I noticed that on the pics of the Mod 15-2's your grips have a diamond on than. I have a 15-2 K750XXX(all numbers mach on the gun, grips included) but no diamond. When did S&W change there grips or are thay something special?