Wenge is a denser wood than ovangkol so I think that (among other things) contributes to a tighter and slightly better sounding B string on a 5 string.
Consider that the heavier wenge neck lends to the neck dive on the Thumbs (which I combat with a good wide strap). The Fortress likely doesn't suffer from neck dive since it has a longer upper horn than the Thumbs.
Of the three that have made it into this thread,...I'd get the old Fortress. I just could never get on with the aesthetics of the 'Vettes
As far as the questions concerning the red 'Vette for 1500,...that does indeed look like a wenge fingerboard,...the neck is likely ovangkol and it is likely a German made Corvette STD. I'm unsure when Warwick move production of the Standards to Korea but I think it was after 2008. The current finish on the Pros is more burgundy and is an oil finish. The 'Vette in the ad appears to be a more red poly finish which makes me question if that is indeed bubinga. The grain looks closer to Swamp Ash to me which is appropriate for Corvette Standards and
AFAIK Warwick didn't use poly finish on bubinga.
If you can get serial #s,...these will tell you a bit about the basses and help suss out any inaccuracies in the listings.
Warwick Differences? 
