Passing an unwanted guest to the offline wallet and back again over the USB key, seems like the one main vulnerability of Armory.  I was thinking of re-partitioning an old USB flash drive to be just large enough to store most transactions one might make to/from the offline wallet. 

I was wondering if that sounds like a very good idea and, if it does, if the developer had any idea about how much space might be a good compromise between usability (key not usable if too small) and enhanced security (space for unwanted guests if key partition too large).  As the wallet is offline, I don't anticipate ever sending to multiple addresses, or having especially long blockchain entries.  I have imported private keys for this just in case anything were to go wrong with the armory wallet or if support on Armory were to end abruptly.