There is no connection between archival quality and the use of blix or bleach-fix. The argument is removal of silver from color films which affects grain, sharpness and color repronduction. In E6 films, it can also affect whites.
So, your question misses the true problem.
A post development treatment of color film (any type) must remove all silver metal and all silver halides. The fix part of a blix or a bleach-fix does remove all silver halides present, but the bleach part may not allow removal of the silver metal completely and that is the problem. It does not affect image stability though.
Wow, thanks so much. So, my real concern would have to be image quality, not so much stability. You said "the bleach may not allow removal of the silver metal completely", does that mean that sometimes it *may*?
Can you guys *see* the difference in films that have been processed in blix vs bleach and fixer chemicals?