The link on profiles (for those with permission) is a good idea - and I think there should be a template hook in vBulletin to make it very easy so I'll definitely add that on my to-do list.
The PM style auto-complete for usernames I would also like to implement, I admittedly simply didn't bother with it for the initial release just so that I could get the code out and released before I tinkered with any more fancy bells & whistles! Also on the to-do list for next release version.
Cheers for the feedback & good suggestions