- Key well is cupped so all key rows are near-equal distance; you don't need to move your hand around.
- Key columns are vertical, no angular stretches for your fingers.
- Modifiers are right under your thumbs, no hand movement required. Emacs users rejoice!
- You can remap those keys under your thumbs. I remapped one to control-space ("set mark" in emacs), which is lovely.
Adaptation really isn't that hard. Unlike "big" changes such as switching to Dvorak layout, adapting to the Kinesis Advantage doesn't take much training. It took me about 2 weeks to get back to speed, and much of that was because I was a sloppy typist when I switched. (The Kinesis pretty much forces you to touch type correctly.) By contrast, switching to Dvorak took me about 2 months.
EDIT: for completeness, a couple disadvantages of the Kinesis: 1) Escape key is not mechanical, it's on a row of gummy-feeling function keys. vi/vim users will probably want to remap one of the thumb keys to escape. 2) It's not great for gaming, I still use a traditional-layout mechanical keyboard for games.
As an aside, I believe recent models have mechanical esc and function keys.
But to your point, it's a leap that most people have to take on faith, as they probably can't find one to demo. I had the good fortune of having a coworker with one so I could try it first; a couple minutes with the Kinesis was all it took to sell me. The same's happened in my current office; now 4-5 people use them. But to the average person who can't try before they buy, it's a leap, and I'm sure that's hindered adoption significantly.
You're right on the current model's escape/function keys, looks like they're mechanical now--excellent! All of mine are older models.
The Advantage 2 resolves this issue. :) I'm looking forward to getting mine later this year.
For gaming, I use the Razer Orbweaver, but while playing Dark Engine games recently I found it problematic because there's not enough room for all the mappings I wanted to use (gadgets, special weapons, quicksaving/loading). The situation would probably be even worse with strategy games.