It's depressing that only one in five of these keyboards is ergonomic. If you're a developer today and you are planning on typing on a keyboard for at least the next ten years, picking any other keyboard than an ergonomic one is a guaranteed path toward painful and permanent pains in your wrists and forearms. Switch to an ergonomic keyboard today, you'll be glad you did.
I've been typing on keyboards for the past 20 years, no pains at all. I credit it to Dvorak, myself.
Make no mistake, though: Dvorak is an aggravating factor in carpal tunnel syndrome. The faster you type by moving your fingers only and not your hands, the more likely you are to start feeling the onset of CTS.
Ironically, the best way to make sure you won't suffer from CTS is by typing with just two fingers.