I started using Colemak 18 months ago. My old QWERTY speed was 90 WPM. It took me 3 months to reach 80 WPM on colemak, and another 6 to exceed 90. My speed is now 90-95 WPM.
I'll make a pros and cons list of the switch, compared to Norwegian QWERTY, hopefully useful to prospective users. Weigh them for yourself.
Pros:
- Somewhat more comfortable and less awkward typing
- Somewhat faster
- Consistent across all platforms
- US symbol layout makes []{}~^ easy to type
Cons:
- Takes a long time to learn, don't expect to ever make up for the lost productivity
- æøå require Alt Gr -- somewhat slow and awkward, though I still type as fast as I did on QWERTY
- Expect some trouble typing on Norwegian QWERTY. I recommend looking at the keyboard when typing on that, to prevent mentally mixing up the layouts. For a while I typed really slow on NQ, but then I spent a few days relearning it, and now I can type fast on both.
Note: If you're having pain issues, switching to a light tactile keyboard will probably help more than switching layout.