Well, it's been a little over 3 years since I've switched to Colemak, and now I'm going back to Dvorak.
I never got my speed and accuracy back to what I had before. I tried some typing exercises (typing out paragraphs), and while that has started to help, it has also shown me that I just don't really like Colemak.
Colemak favors letter clusters, like typing several letters in a word with one hand, whereas Dvorak favors hand-alternation. I think I prefer alternating hands.
Anecdotally, Colemak leaves my forearms and wrists tired. Especially my right side, for some reason.
Anyway, back to the "I can't type" phase again for a few months.