I just by chance came across this plugin. I have not used it yet, but the possibility of using a role based slug is fantastic and something I was looking for for a long time. I would need it to work with the buddypress members pages though.
I know BuddyPress has not introduced the WP rewrite API, but will do with the next release. Do you think it would be possible to adapt your plugin to work with buddypress too? Or basically create a new plugin from yours?
Anyway, I will try the plugin and examine the code a bit. But if you have experience with the issue before, then I will be glad of any help.
Rewrite rules scare the hell out of me :)