I've been using Colemak for just about a month now, and I think I'm at my first plateau. As a reminder, I came here from around 100wpm on both Dvorak and QWERTY, using Dvorak as my primary.
I've been monitoring my progress for this month using the Top 200 English words test on 10fastfingers, since there's some kind of fairness between tests in that they're relatively the same difficulty, but I can't memorize the test because the words are randomized. A few notes on the test: It's much harder to start a flow on unrelated words strung together, so it's not a great representation of my speed typing actual sentences. It also counts a word as "wrong" only when you hit space, and there's no way to go back. This test is very poor at tracking accuracy because it only tells you how many words you got wrong versus right.
Attached is a graph of the test points that I've tracked. I started on day 1 at 9WPM, and my speeds gradually increased at about 16 wpm per week for three weeks. Since then, I've been stuck at around 55wpm on this test. My accuracy needs some work, but I need to find a different test to use for that, so I think that's my next step.
Once I've gotten my accuracy solid, and typing doesn't feel awkward, I'm going to start incorporating Dvorak and QWERTY back into my typing. I'm not sure which I'll start with, but I'm going to try to maintain all three and see what happens (yes, there's no real benefit, and yes, I am slightly insane).
Going to look into better accuracy-tracking tests now!
(Minor edits for grammar.)