I just wanted to make a post saying that I have done quite a bit of manual hacking of phpbb files on my site to properly get things integrated.
I am not using your plugin, rather, I am using one made by the guy over at
www.mehdiplugins.com/misc/phpbbjoom.htm which works with comunity builder with some minor hacks of his code. I haven't really started taking a look at your work yet. But one thing that his setup does really well is direct integration. It is a wrapper of sorts, but it works in a totally different way. Maybe you have seen this stuff, but that to me is a key element.
I hacked my phpbb so that all the profile links on the forums link back to the CB profiles. I am also in the process of writing a script that will allow me to use the CB profiles to alter my forum user profiles settings (things like signatures, and what not).
I don't know if your script does that, but to me it is pretty essential to have the ability to edit the forum settings and profile information right from comunity builder. Does yours do that? I am afraid to install it right now because I don't want to screw anything up. I may take a look at it though later with a test site on a different server.
Granted, his method requires quite a bit of overall php hacking, but it looks better in regard to the end product.
Just throwing it out there. Chow!