First off, the natural tendencies of people is to fly the most competitive ship they can find. I have lines of people waiting for CCZs, but I can't get a carrier jock if my life depends on it...
Secondly, outside of the I-CCZ, there are little complaints against the "line" BCHs, (F-BCG, K-C7, R-NHK/RHK, G,Z,L-BCH, and Hydran whatever-it-is). It's the "fancy" BCHs (like the shock-bearing F-BCJ or R-KHK), Limited build (F-BCF, R-KCR C7 variant), BCV (Hydran OS IIRC), and other "limited" versions that cause the most grief. Therefore, I'm thinking that the OOB demarcation line should be drawn around that point (line BCHs unrestricted, Fancy BCHs and up restricted).
I'll see if I can work that system into my theoretical OOB...