I've used colemak for ~3 years and love it. I have it set on a programmable keyboard, with matrix layout, that I built myself. So I can take it with me if I have to switch computers. When I'm on a laptop, my body knows it's qwerty time, and I see no slow-down.
I had a burst of ergonomic problems that made me switch. I have had zero problems since, and I work just as many hours.
I can recommend colemak.
I learned it by typing a novel from an author I wanted to learn writing style from (Murakami, pinball 1973). Took me maybe a month.