That would be a great way to build a CMS including a forum, but I meant more the appearance: Phorum is bare, minimalistic and did not seem to have as many themes available. I think it's sort of the point, a no-BS forum for tech geeks.
I like Xenforo, a lot. As it turns out, I misrecognized it as vBulletin with some plugins on another forum, and really enjoyed it there. Snappy response and visually elegant. I think that's a winner.
I wish I could get excited about phpBB and to a lesser degree, SMF. Under the hood, SMF is probably a better forum, and it has many more intuitive and useful features, but it's also, just, pukey. It looks kludgy and has some stupid nerdy aspects that may it excruciating.
(And while I would love to get involved with one of these projects, there's a time deficit plus an unwillingness to beat back the day-trippers.)
The final running includes Xenforo, Phorum, and myBB. Thanks all for the advice.