@Newby: Yes, basically. Say I have a have a set of flags for masters, and take someone straight from no flags to that. Accesslevel won't do it, unless I give them a flag, give them the access level, then give them back the flag, and flags has me manually type in my flags. Say, I have the following flag combinations:
master ACDEFGHIJKLMNOPQRSTUVWXY
admin AFLNSTU
member FU
other LSTU
other-low LU
Some of these would be fine to just manually type in really quickly. Others would be a pain. And I'm just horrible at remembering all these combinations. >_> I found that usergroups might make it easier, or might make it harder. Knowing how to mod my plugin for access levels, so instead of toggling, it will set the users exactly to those specified flags, or using + and then an access level, or - then an access level, to add or remove that level's flags, could replace this idea.
Dealing with overlapping flags? It would just give that member the flag. It would give it again, and since there's two (or more), a little process would change this, so if it is the case, the flag will be processed for modification - then setting it back to only one of that same flag on the user. An example for a user in 'member' and 'other' usergroups:
/whois *MyGenericPerson@Azeroth
*MyGenericPerson@Azeroth has flags FLSTU (In usergroups member and other)
Basically. Also, did I miss anything?