Can't help you on the grips question specifically, but I can suggest some alternatives. Having experienced a bout of carpal tunnel last year, I finally came around to starting using work gloves. Even a relatively thin layer of leather provides an impressive increase in comfort and cushioning when using the standard grips (and all wood-handled hand tools, etc). I just buy the cheapest full-grain (i.e- not suede) pigskin, goat, or cow hide gloves I can find (the Northern Tool store near me has had the best prices), but of course there are options that have even more padding.
Something else you could try is to wrap your existing grips with leather (like sold for steering wheel wraps) or coban tape. The coban is probably less durable than leather, but a few layers of it provides a nice cushion, and it's easy to apply. The coban I bought was through a gun supply place and came in camo pattern (McNett was the brand I think) sold for wrapping stocks and hand grips, but my wife tells me that gymnasts and cheerleaders also use coban to wrap ankles and wrists, so you can probably find it at athletic supply places too.
-otus
