Sorry to break up your little posting spree, but I loaded ctf_convoy on a couple of weeks ago to test and while it looks great and is a neat idea, it's a horrible map for 24 players. Probably horrible with even less. It only has 2 narrow crossings to take the intelligence between the two sides which are very easily locked down.
If you really want to try it, we can, but I only recommend it with very low population.
I'll check out ctf_cancer to test.
Note: ctf_convoy has a new version:
http://www.fpsbanana.com/maps/45247