That is a seriously sexy Thumb. As you can tell by my comment in that thread
What Schlo said is right....Thumbs are a unique beast, with some neck dive. Although I would say it's more of a neck sit. As it kind of stops at horizontal....but that does make the first 3 frets awkward for some. Of course if you don't plan on standing with it much....no worries at all.
On the flip side...the Thumb is Warwick. Really is Hans Peter's first truly original design. And it's BADASS. Still to this day, there's nothing like it. Original to the core.
If it was ok for an old timer like Jack Bruce...it's gotta be ok for a young hip fella like yourself
Edit: I see that Thumb is sold. Was it you tidr??