What have you guys heard on the Gen 4 pistols? Are the slides interchangable with previous generations? If so, I think a 4th gen G21 would be a good companion to the 3rd gen G20. Between the two guns, you could shoot pretty much any common autoloading big bore cartridge and then some: G20 slide on either Gen 3 frame or Gen 4 frame - 10mm stock .40 S&W .357 Sig 9x25 Dillon That's 8 configurations right there. G21 slide on either Gen 3 frame or Gen 4 frame - .45 ACP .45 Super .400 Corbon And 6 more configurations right there. Fourteen configurations... not too bad for two slides, two frames, and a few conversion barrels.