Years ago, I was tempted by the promise of Dvorak. I spent a lot of time typing and the idea of being faster and possibly preventing strain or injury was appealing. I worked on it for a little while and saw some promise in it, but the CTRL-xcv not being there was enough to make it very annoying. I was also afraid that my typing at other people's computers would suffer, and that I might be seen as a prima-donna for having a weird keyboard at my desk. (I changed my physical keycaps to Dvorak, without that I felt uncomfortable.) I quit after a short time. Later I saw someone propose switching only the CTRL-xcv with qjk and leaving the unmodified letters in place, but I don't know if that is easily done or if it would have been confusing. By that time I had switched to a split keyboard, which is not as easy to switch the keycaps on, and it really felt better so I wasn't too willing to give it up to try Dvorak again.
Just yesterday I bought a non-split wireless keyboard, so I had the thought of trying Dvorak on it. I stumbled into the Wikipedia article on Dvorak, and it reminded me of the trouble I had with ctrl-xcv, but it also mentioned and had a link to Colemak. When I saw the layout I instantly was drawn to it, seeing ZXCV in place and the Wheel-of-fortune (most used) letters in the home row. And the idea of error correction with caps lock seemed absolutely brilliant. I knew then that even if I decided to stick with qwerty I had to have caps lock as backspace, that is so simple, like the paperclip but so perfect. I'm shocked that keyboards haven't had backspace there forever, you know what I mean it just seems so right.
But before investing in learning, I wanted to be sure this was the one to go with. I saw your list of other alternative layouts, and Capewell-Dvorak and Capewell seemed tempting as well. The really bad thing about Capewell is that he isn't finished with it, and I don't want to learn something which is going to change. But Capewell-Dvorak looked really good. I don't really know if the extra alternation of hands that a Dvorak based layout has compared to Colemak would help or hurt. The reason I chose to try Colemak instead of Capewell-Dvorak was 2 things. First, I figured anybody who advocated capslock for backspace is someone I'm inclined to trust, and the second is your enthusiasm. You seem to really feel that Colemak is a good layout, and you say it is final, no more planned changes. Capewell is not as enthusiastic about C-Dvorak, and the way he is developing Capewell implies that he feels C-Dvorak isn't the best you can get. He also implies that he might rearrange C-Dvorak as well and that it may not be fully-finished.
I know you suggest not to but I have moved my keycaps to match Colemak- I need it to feel comfortable. My initial typing is very slow but I have to do more of the lessons.
I still have some fear that I will be slower when helping other people with their computers, which is something I do often. However these days I do much more typing at home than I used to so I think the trade-off if it ends up being one will be worth it. I also think I can get away with a weird keyboard at work now. (I hope this doesn't end up getting me fired :) )
I would like to close with 3 thoughts. First, please do not change any of the main keys in the future, I really want to feel that the layout is here to stay. (I wouldn't be offended if you tweaked the multiliguals if you felt it needed). I hope someday a keyboard manufacturer will make a split-keyboard with Colemak labels, that would be for me the best of all worlds, and if the layout is not stable it would be a disincentive for someone to make hardware. Second, perhaps someone can write a nice introduction to Colemak on a blog and submit that or the homepage to the social news sites like slashdot, digg, metafilter. I would like to see this get a lot more users. Third, it seems that the Wikipedia article on Colemak highlights a few of the advantages more clearly than the colemak.com homepage - the capslock being used for corrections without moving off the home keys, and the 10 most common keys being in the home row. I know the 10 common keys part is a bit redundant with the "There are 35x more words you can type using only the home row on Colemak." but I think it might make the advantage clearer to some people, and highlighting the Capslock innovation I think especially would be important.