I've got a propane-powered airsoft replica of my S&W sigma. I bought it for the sake of training. I wouldn't want do force-on-force or games unless my opponents had several layers on, this pistol rips through soda cans from 10-15ft away!
It's about as heavy, the slide is looser, and the trigger is so much better.
I use it for trigger-squeeze, drawing, and magazine change drills.