Just to bring you up to date on this, I purchased the S&W replica pellet (lead pellets) pistol. The weight of the pellet gun is within 3 grams of the actual S&W .22 cal pistol. I am as accurate with the pellet gun at 10 YARDS as I am with the .22 cal. (96% which isn't to shabby). The only difference beside the bang, is trigger pull. I have the option of shooting it either single or double action (with the co2 pellet pistol). Single action trigger pull is identical. Double action on the Pellet pistol is heavy. It is a perfect fit in my holster, and I can practice draw and fire (albeit one shot at regular trigger pull, not double tap). I don't use it in lieu of regular shooting, but in addition too regular shooting. I have heard that in some circles, dry fire is preferred to actual firing as you do not have to deal with the recoil. I am not sure I advocate that, but I am not an expert. I do know that I prefer seeing something hit the target rather then pretending to see it hit the target. I also feel I need to be sure and manage the recoil of my .45 cals. also.
I have recently purchase two air soft H&K replicas. While they come close to my Glock model 30 they aren't exact replicas. That being said the fit nicely in my holsters. I have spoken to several law enforcement trainers, who recommend using the Air soft guns for training, unless you want to wear bullet proof vests, and have at it. Shooting is shooting, training is training, pellet guns, Air Soft, dry firing, actual firearms, more is better (at least I think so).
Another thing is that 50 rounds of pellets including the co2 costs about $1, compared to $4-$5 for .22 (if you can find it), $25 for .45 cal...., and it's a bunch of fun too.