Yes, it was talked about in the 4a forum - same thread http://www.naturallycurly.com/curlta...sing-link.html
I don't see what's so hard about saying 4a/3c, 4a/4b, etc. Its something that many of us are more familiar with than making up a new category.
Many if not most of us curlies do have more than one curl pattern. I'm 4a/3c with some waves, tighter curls, looser curls - all on one head. That's partly why I stopped putting my curl pattern in my signature. Its different for everyone who sees my hair.