I don't know if I can offer any hard and fast answers to your questions, but I would like to toss this out there for your ponderances...
You haven't mentioned actually firing the pistols, and haven't eluded much to your shooting experience in general. Now, something I have wondered over for a while is exactly 'what is being looked for' during the course of 500-1000 dry fires? I'm really not trying to be a terd here, but with todays common types of handgun sport, the picture perfect trigger isn't even known of in the same regards as in the old days of NRA Conventional/Bullseye shooting. With a typical duty/defensive or run-and-gun game type handgun, if you're doing your part, you won't notice that little "maybe" creep in there during live fire. And speaking of live fire- 500 to 1000 dry fires just doesn't break the pistol in the same as the equal amount (or even half) the amount of live fire. I don't think I'm a trigger snob, but I do enjoy nice ones. I've also been working on firearms for close to 21 years now and tend to try to remain ever observant in learning causes and effects. Not lumping you into a group here, but I think of the car enthusiasts in how they have tons of tuning and diagnostic equipment. They'll spend every weekend in their driveways always wondering if they have a perfect tune on that '69 carbureted classic. The thing may be better than when it left the factory, but eventually they'll find something wrong with it if they just manage to look long enough. Personally, I think anything over 50-100 dry fires won't do much but pass the time on days too cold, too hot, or whatever to actually launch projectiles. Go shoot and do good things.