I'm a big fan of the Kinesis keyboard. I use Emacs, and I was starting to have some RSI symptoms from the ctrl/meta key combinations when I discovered the Kinesis. Moving the modifier keys (except for shift) to the thumbs is a huge improvement.
The arrow key layout is actually one thing I don't like about the default Kinesis configuration (the bottom row for the left hand is backquote, backslash, left arrow, right arrow, and for the right hand it's up arrow, down arrow, left bracket, right bracket). I remap these keys to put all the arrows on the right hand (in vi order).
The arrows are weird and the less-than-normal function keys are suboptimal (and I've used these keyboards long enough to run into some very rare firmware quirks and odd choices made by the maker). However, since everything else is so AWESOME - the hand position, being able to do CTRL+ALT with one thumb while keeping all the fingers in normal position and being able to map the other two mod keys to ALT, META, and then CapsLock to Hyper (for window management only, in my case)... oooh, this keyboard rocks for most things, including coding and gaming (assuming the game supports changing your keybindings to optimal keys - WoW does, for example). I think I have four of them, and my girlfriend prefers hers to normal keyboards. They've totally eliminated my incipient RSI. (rave, rave, rave). However, I do wish they'd fix the little issues that remain in some future board, so I don't have to keep musing over whether to buy a Maltron to compare.
The arrow key layout is actually one thing I don't like about the default Kinesis configuration (the bottom row for the left hand is backquote, backslash, left arrow, right arrow, and for the right hand it's up arrow, down arrow, left bracket, right bracket). I remap these keys to put all the arrows on the right hand (in vi order).