I am not going to talk about the advantages and disadvantages that a different layout may have over typing speed and comfort as these were discussed previously.
I would like to expand the topic into the medical advantages and disadvantages of different layouts and keyboard shapes.
I hope you would not mind!

The reason for this is that I have constant pain in my right wrist as I sprained it 3 times (bicycle and snowboard crashes). I am also prone to develop Synovial Cysts (ganglion cysts) in bots of my hands, which cause the pain to become unbearable if I keep my hands in one position for longer periods of time (sleeping, typing, etc).
I have slowly come to realize, as many of you already have, that the QWERTY layout is slightly inefficient. But I also think that, for me at least, most keyboards are inherently inefficient because of their shape, with the key rows being parallel right in front of me, forcing my hands into an unnatural positions for extended periods of time. I know that there are keyboards that cater to this (e.g. the Ergodox) but I love more the way a normal keyboard looks, that's why I haven't moved to a split design

Because of the above, I wonder if a layout with modifiers in 2 columns in the center of the keyboard and the alpha-numeric on each side of the modifiers would be more useful and more comfortable to use.
What do you think it would be a good layout for avoiding medical issues (like Carpal Tunnel)?
P.S. I haven't read thoroughly all you posts until now (work first) and If I'm rambling, please tell me and I'll crawl back into my hole

P.P.S.: if any of you have wrist pains and/or ganglion cysts, there is the Apireven cream which has helped me alot and even helped me stay away from surgery (in pharmacies here costs 5 euro)