g1smd - 12:01 am on May 27, 2010 (gmt 0)
As far as crawlability and SEO, vBulletin is getting better out of the box and vBSEO does the rest.
Seriously. Have you actually stopped to look at how many Duplicate URLs each thread and each post can have in vBulletin? It's insane that schoolboy design errors remain five years after they were first highlighted.