I think your idea is stupid and without merit. As it is, class 3 to 5 is gradational, and represents an easily understood increase of difficulty. To further break up class 3 and 4 in just plain stupid. People who boulder realize that they are bouldering, and not half way up the north ridge of Stuart. And most people with even a little experience know that the distinction between class 4 and say 5.3 will be fuzzy.
I like Bryan Burdo, but his system always seemed like re-inventing the wheel to me. If you can't sit at the bottom of a 5.9 offwidth and know that it will take radically different skill and mindsets than a slab, handcrack, or sport route, then you are a lame MF'er.