Any question answered...

If you are using a BSA bb with internal di2 the bb cups may have threads that are too long - Chris King and Hope bb would not work in my Isen as their threads would block the hole from the bb to the chainstay. - I had to resort to shimano as the threads are shorter.

Would it be possible to turn down the length of the cap with the threads on it? I know what you mean about the Hope BBs (I don't have any Chris King BBs... yet) but I can't see any real reason why the threaded sections are so long on them.