I agree with the comments already mentioned on why we love krav. However, i just started Krav and learned that KM does do "colorful belts". It seems that we just don't wear them and it is refered to as level 1,2, etc... I trained in a traditional MA for about 10 years and didn't feel pressure when it was time to get another belt or be promoted. It was a great goal to achieve.
Sorry if this swayed off topic a bit. Don't get me wrong, I love my traditional MA and love KM. They both have pros and cons, I think it is about taking something from both and making that material yours and having it work for you.