I have very recently made the switch to Colemak. I am not at my full QWERTY speed yet, but I'm getting there. I used to be between 80 - 100. Right now I am somewhere between 50-60.
My motivation for switching had nothing to do with speed. I was trying to avoid hand injuries. But if I can come out of this as a faster typer, I certainly won't complain.
I use my computer all day, everyday, for work and for play. After a hard day I was getting pains and cramps in my fingers. Colemak is designed to prevent that because the distance your fingers travel is much shorter, and it is far less common to use the same finger twice in a row.
I started learning Colemak about two months ago, for the first two weeks I only put in about 1/2 hour of practice per day. They say you should practice at least 1 - 2 hours per day if you want to learn it more quickly.
I've been using Colemak full-time for about a month now, and I haven't experienced any finger pains in that time. It's still early, and I haven't reached full speed yet, but so far its looking good.
While I'm typing on Colemak, I can't really
feel that it's better. But when I have to type on QWERTY, that's when I feel the difference. QWERTY is much harder on your hands, the amount of finger movement is much greater.
Before I learned that Colemak existed, I was planning on learning Dvorak. But Colemak is so much better. It is designed to be learned by people who already know QWERTY, but want/need something better. It keeps all but one of the punctuation keys the same. It keeps most of the common windows shortcut keys the same (ctrl+A, ctrl+Z, ctrl+X, ctrl+C, ctrl+V), and it keeps the entire bottom row almost completely unchanged from QWERTY.
In the beginning you really have to force yourself to use it. If you don't, then you will never make the switch. I think I started to switch once I reached about 25wpm, but I was still using QWERTY like a crutch from time to time.
This is the training I was using in the beginning:
http://www.learncolemak.com/lessons.php
After I went through that enough times, I just started doing pure speed tests.
I'm over 50wpm now, but that's mostly due to mistakes, I never have to hunt for keys. I just sometimes instinctively hit the wrong ones. But that continues to improve every day.
For games, I could remap all the keys in game... But instead, I just hit WinKey+Space to switch to QWERTY before I start a game, it takes about .3 seconds.
More Colemak info:
http://www.colemak.com/wiki/index.php?title=FAQ