I think the required linear progression between flag pickup locations is the big issue with the mode. If it were just three flags and players choose which ones to go for and when, or even split up and try to snag two or three at once, I think it could end up working. I emailed Valve about possibly adding support for that like they did for A/D CTF, but of course I haven't gotten anything back from them. Then again, I'm not one of the site's higher-ups. *shrug*