Do you already have an Azeron or other "chording keyboard"?
I've used other split keyboards, handheld chording keyboards, and desktop chording keyboards.
Chording keyboards are AWESOME for one-handed typing, speed typing, and gaming, but have an enormous learning curve and rely heavily on muscle memory.
I had a Twiddler 2, Twidder 3, and AlphaGrip.
AlphaGrip and TrueGrew on my favorites, but neither are immediately easy. Learning curve for both.