I made two custom skins, a couple modifications to the profile, a few mods, but mostly the phpbb-seo.com mods as I install on every forum I own.
I upgraded to phpBB3 recently, didn't lose ANY pages on google, it wasn't for the faint of heart, but the whole upgrade process wasn't.
A lot of great documentation and the help of the administrator of this forum helped me with that. I'm just happy that I won't have to do phpBB4 for quite some time.
The site has over 100,000 posts and growing. It has basically every mod from phpBB-seo.com and all that really shows up on google is the topics, forums, profiles, and index page. That is exactly how I want it.
I wouldn't recommend that people use the "member names" for the profiles -- if you're applying the mods to your current installation -- because the fancy names with weird encoding will give you a headache. I don't think it really affects page rank.
I probably shouldn't have used title as the url because a lot of the topic titles are crap and wouldn't mean anything to people on google, that goes a long with the title. I don't regret it though, its useful when your forum mebers are linking people as well. Take some SEO, give some user friendliness. I'm experimenting -- on the forum that I just launched -- with using just the "topictitle" and I'll report back my particular results.
As for page rank. I need more backlinks, but I think its coming.
Thanks for checking it out.