The methodology below avoids having to download the whole blockchain to a dedicated offline computer (which is required with Armory).
That's wrong. The offline Armory does not use the blockchain or bitcoin-qt. Very low system requirements.
Your steps look good, but probably are too complicated for the majority of users. Also it forces you to reuse one address.
If you plan to do frequent transactions and have enough space for block chain and Armory database, you should check out Armory.