Hello all: Thanks for great input.
Ran more tests yesterday in which I removed all char formatting with IXgen/FM6, then reopened/saved in FM8 and generated the book: all was well. Also, book that was crashing in FM8 definitely survived without our IX template. BUT: the generic index maintained the char formats, and survived. Anyway, Adobe has been in touch with this, and I sent them a zip of books, test notes, and crash files. They have now been able to reproduce the problem and will get back to us. Kanti