Good point, and I agree as for not putting the burden on the user, that's why personally I'd used the bloom filter approach to quickly disable password input (n

Good point, and I agree as for not putting the burden on the user, that's why personally I'd used the bloom filter approach to quickly disable password input (not remove the field) and display a short explanation for the redirect. Normal users would see nothing out of the ordinary, and SAML users would see what they see now plus an optional explanation for what's going on. I have received my fair share of confused calls regarding (microscopically) more arduous login processes and presenting fewer people with any change at all helps tremendously with reducing those calls.