i wonder if another reason to avoid exporting Armory linear deterministic privkeys is if you reveal that privkey on your phone along with perhaps the master public key, can ALL your privkeys be determined similar to how it can be done with an xpub+childprivkey in HD wallets?
molecular would probably know.
I have no experience with the armory linear scheme in particular, but I would assume all type 2 deterministic schemes suffer from this problem. I can say it for sure for the classic electrum 'linear' scheme.
My solution:
don't ever export private (sub)keys (my trezor nicely keeps me from doing that even when I'm drunk or whatever).
i think that is right.