I have a G-20C and am pleased with it. I have been a die hard S&W guy for many years. To "upgrade" I had little choice if I wanted to stay with my beloved 10mm.
Versitile is the word that comes to mind. Conversion barrels from Lone Wolf (and probably others) in .357 Sig, .40 S&W and 9X 25. Lone Wolf also makes a .45 slide (3 different lengths actually) that will work on the G-20. My Glock will be 5 caliber capable by year's end.