I'm not sure I'm getting all this either, but if you want new users seeing only 2 nodes, or however many, then set that as the default for the Registered group. Or just rename the Registered group to something like "Limited Access" or whatever. The bottom line is you seem to want to be able to assign some users to multiple usergroups simultaneously (on signup?), but even if you could do that wouldn't you have to pick individuals to send different signup emails to, and if so I'm not sure that would be any quicker than having to manually upgrade them from the admin. Just sounds like you guys are *maybe* making things unnecessarily difficult.