Right so I finally get try one care of Andertons in Guilford. They Set me up in their 'Bass room' with the BTB33 into a nice Markbass combo and left me to it. It's a really cool bass: through-neck, barts, 3-band EQ, mono-rail bridge. However, after playing for a while I realised that I wasn't getting much more than a standard 5. So yes it's up a forth which is OK if that suits your music but other than that, it's the same number of notes as any other 5-string 24-fret give or take (it has a weird s-shaped neck end). Also the 33" scale was pretty much undetectable in comparison with my GB 35" scale. Similar position and string tension. (In contrast, an Alembic SC with 31" scale reduced the strings to floppy butter making everyone Stanley (almost) with sheer effortless of playing.)
So my verdict was not to buy, but for someone without a 5, or entering the market for a 5, it's a hell of a bass for the money...