[bsimpson]

I've heard people complain about this approach because if you tried to refactor, someone could have written class = "large rounded btn" in one place and "btn rounded large" in another, making finding all the variations more cumbersome.

That doesn't mean it's a bad approach, but that is one concern I've heard about it.

[tobr]

Not sure what you mean - order of classes don't have any effect with regular css .class selectors.

http://jsfiddle.net/n1a9Lew5/

Edit: Oh never mind, I now realize that you're saying it's harder to find markup that uses a specific combination of classes. That's probably true, sorry.