I've done it in a G20, G29, and a Smith M&P 10mm. No issues at all, accuracy and POI was the same.
That said, I've been able to get 10mm practice ammo at virtually the same price as 40 S&W. I tried it primarily just to see if it would work in an emergency. I don't plan to make it a regular practice unless 10mm ammo becomes unobtainable. I've not bought any 40 S&W ammo, but have been given a few hundred rounds from a guy who sold his pistol and no longer needed the ammo
