Turning this thing on its head, having a 10mm handgun, then dialing it down if desired is a better situation than trying to bump up a .40 S&W. I have owned a number of 10mm autos and revolvers and always appreciated the wider ability to tailor loads. If I had a .40 and was not satisfied with its performance, I'd think about getting a 10mm. The .40 is more of a duty cartridge, and lacks the versatility of a 10mm that reloaders can enjoy.