usergroup setup in this scenario

[Benj]

I need 2 user groups one normal users and one "promoters" both with virtually the same permissions but need to be different user groups because of template / phrases changes between groups. i then want to offer a plus account (available to both groups) with a few added extras you know normal stuff i dont really want to create 2 more user groups one for normal users and one for "promoters" so how would i do it? make a secondary user group called plus account and make it the secondary user group for plus users? would my user group template conditionals still work correctly?

thanks in advance