I've been looking at the Kinesis keyboards to try to get some relief from wrist pain. Which do you use? Have you tried the MS Natural, or did you go straight to Kinesis?
Kinesis can strain your thumbs. I used one for 14 years. Still got major wrist pain and really bad thumb pain. Microsoft Sculpt Mobile and that style of keyboard ended up being my best option.
I initially had rsi pains in my wrists and pinkies, after I recovered I switched to a Kinesis and was convinced it helped keep the rsi away for 2 years or so.
Recently the pain came back worse than ever, this time accompanied with quite serious thumb pains, I certainly do not blame the Kinesis as it is most surely a combination of many factors (poor habits, stress, workload, etc.), but the layout does increase the load on the thumbs so I think that contributed.
For now I have switched back to a cheap Microsoft dome keyboard as it is easier to type with using only my forefinger and middle finger (and easily allows me to avoid using thumbs and pinkies).
Of course this is all just my personal experience, for years the Kinesis was lovely and I may still go back to it, as always YMMV.
I use the Natural. I bought a Sculpt, but took it back because of the top row of keys being so small, and a couple of other gripes. I bought another Natural, but I always ponder the Kinesis line. Besides the unknown experience, the price is also a factor.
My cube-mate has a natural and I use a kinesis. We both thing the keys on the kinesis have noticily better action, but he just can't (doesn't want to) wrap his head around the grid layout. Unless you have very small hands, or you just absolutely hammer on your keyboard, it would be unlikely for the kinesis to make your thumbs sore. The space button on the ms naturl is junk compared to cherry mx brown switches.