I have both JVC FXT90 and Fischer DBA-02 MkI (same as the B2). The FXT90 are much bassier, and don't have the startlingly clear treble of the DBA/B2. The JVC's do have a nice clarity, and are much more of a "mainstream" sound quality. But my old ears prefer the DBA balance, especially with better tips (Shure grey single flange or large dual flange) that improve the DBA bass quality. I haven't used the FXT90's for a while, but I've been using the DBA's nearly every day since I first bought a pair in 2010. I'm on my second pair now, and BTG Audio put in Westone-type connectors, so they are essentially recabled.
Have you tried Shure Olive tips with B2? Would you recommend dual flange tips over olives?