I know I shouldn't speak of such heathen here, but VBulletin board has a basic and advanced option for BBCode which I always found useful. I don't use basic myself anymour, but it was useful for inexperienced users (which I was once upon a time).
Also, I notice that the JS on phpBB 2.0.4 is actually horrible, it is pretty big for what it does. I re-wrote it for my own board theme (Haravikk.com
), seems to work fine for all browsers.
As far as bandwith goes, it could be useful if admins could turn off BB controls (but not BBCode) which would cause them to instead be replaced by a link to the BBCode FAQ