Thanks for the insight, LSP. You have given me a lot to think about.
A little back ground... I hate pocket carry. I use this method only when I have no other viable option. Even if my M-642 is primary, I will tend to carry it on my ankle. Only if I am wearing shorts does this change, and if I am wearing shorts, I can usually get away with an untucked shirt, allowing me to carry my G26 IWB. There are, however, times when this is not practical, and the M-642 has to go into a Desantis holster and into my front shorts pocket.
I am looking for a good kydex IWB or AIWB for my M-642, (must also be tuckable), which might allow me to forgo pocket carry in shorts, but I haven't found one I like. I've read about Dark Star gear, and I may get one and give it a go. This is also how I would carry a 640 (old or new) should I end up carrying a pair of J's.
My carry M-642 is fitted with the Pachmyer Compac Professional. My range M-642 is also fitted with the Pachmyer Compac Professional. This setup lets me practice with an identical gun to my carry gun, but keeps the wear and tear off my carry gun. If I have non-shooting friends at the range with me who want to try something, I have an old M-60 I load with WCs and which is fitted with Hogue Monogrips. A larger gun would make a better teaching gun, but my wife cannot properly hold and manipulate any revolver larger than a J-frame, so that limits my options. She tends to practice with the Hogue fitted M-60, and that is also the gun she has available at home. I want her to have a DAO with concealed hammer, so the 640 would become hers.
As for the Airlite Ti/Scan versions, I have no doubt the reduced weight would make pocket carry more comfortable, but the reasons I don't like pocket carry are more for the lack of security (certain daily activities can allow the gun to move up and expose the grip) and I don't like the draw (they may draw smooth, but I've never been able to get a truly solid grip on any gun in my pocket). Pocket carry also sucks if you are sitting (car, restaurant, etc).
If I had lots of money, I would probably add an uberlite to my inventory, but for now it's not a high priority.