I switched to colemak years ago, and it's really not that bad. It's a little bit mind bending to learn a new layout, but after about a week or two of practice, your mind sort of "clicks" into it, and it's like you've been typing that way your whole life.
During that transition period you do not have to use Colemak exclusively. You're practicing a new motor skill, and the returns on such practice diminish rapidly after an hour or so per day.
Once you've learned Colemak, you will have to use QWERTY for just a short time each day to make sure you keep those neural pathways from decaying. I did not do this, and I regret it. I do alright on a QWERTY keyboard though; it just slows me down a bit. On a mobile device, it really doesn't make any difference, since the letters are in front of my eyes.