I'm converting from Bootstrap 1 to Bootstrap 2 this week.
It's very revealing, when you see how a platform developer, and Bootstrap is definitely a platform, evolves the platform. The kinds of problems they fix that cause breakage in apps. In this case, they break a lot of stuff, for seemingly esthetic reasons.
For example, in Bootstrap 1 they define a "twipsy" -- which is a little popup that emanates from a link as you roll over it with your mouse. Someone must have noticed that this is very much like what a "tooltip" does, so they changed the name. Not a big deal, you say -- perhaps -- but it is breakage. In my world, I probably wouldn't change it. My philosophy is the worst name is the best name. This is to prevent discussions like this one. If someone said "tooltip is a better name" I would say "give me a worse name and I'll change it." It's a joke like "we make shitty software," but like all jokes it's an eloquent statement of the truth.
If I had to change it, I would continue to make the name "twipsy" work. Avoid breakage and people who develop on your platform will love you, if they actually notice. Okay, they won't curse you in their sleep at night.
I adopted this philosophy largely because I develop on my platforms too, and there never is a day when it's cool to have everything break. Especially because a programmer on the other side of the API decided "tooltip" was sexier than "twipsy." And btw, I think twipsy is a wonderful name! So clever and cute. Maybe it was a legal problem? I don't know, but it is disconcerting, esp since I haven't gotten tooltips to work and twipsies worked great. Oy.
The charm of Bootstrap is its simplicity. You can get a feature running in minutes sometimes, if you stare at the code the right way and get lucky. But it's getting less simple in version 2.0. They did a lot of factoring in some areas, combining types. Not sure what that gets us -- literally, I'm not saying it doesn't get us anything, just that I'm not sure what it is. But one thing is certain, factoring makes the theory harder to grok for the newbie.
By the time Bootstrap 3.0 comes out, we'll likely be deployed with users of our own. Since we pass through a lot of what Bootstrap does, there will be breakage, if 3 is as radical a departure from 2 as 2 is from 1. My goal will be to try to insulate people who develop on my platform from changes in Bootstrap, to the extent I can.