I have a B5 and LOVE it. Light, good tight B string, active preamp that sounds fabulous. However, I'm not sure, but I think the B5 became the B50, which has larger upper and lower horns and I think a wider string spacing. I thi k the B5 has 17.5 and the B50 is 19mm.
Either way, you can't go wrong...
Mediocre Bass Club #476/Acoustic Club #248/Tricked Out Squier Club Member #34/Carvin Club #225