At my dojo we have colored belts as incentives for the kids' class, but for adult classes the system goes: White 5th-3rd kyus, brown belt with hakama 2nd-ikkyu, black belt with hakama at dan grades.
I've traveled to a few other Ki Society dojos and have seen colored belt systems there for adults, so yeah, I guess it's kind of dojo specific. Personally, I like wearing a white belt until 2nd kyu, it's one less thing that this college student has to pay for, and while walking through our rec facility on campus where my club meets I almost feel "incognito" with my white belt on, because I am a beginner but a beginner with 2+ years of experience. It's my understanding that in most other MA's I would no longer be a white belt.
Interesting question though, I've enjoyed reading about all the different systems out there.