I just mentioned a few things about B+ in my reply to another thread:
viewtopic.php?f=28&t=547&start=20#p5118
The short answer is that the current OSPi v1.4 will not work with B+, unless if you are ok with using ribbon cables to connect B+ to OSPi. Specifically, the extra 2 USB ports are in the way so B+ cannot plug all the way down to OSPi. Also the pin headers are slightly shifted in position so the enclosure can’t close properly. The only way to make this work is to keep B+ out of the enclosure and use a 8pin ribbon cable + 5 pin ribbon cable to make the connection, much like OSPi 1.3.
So a new revision for B+ is due 🙂