To clarify - I would only be redeeming outputs that were previously generated on this off-line Bitcoin-QT instance. I would not be redeeming outputs that other third-parties may have sent me, but rather outputs that I have only signed myself. I gain no further information by downloading the blockchain, other then seeing which block my transactions were accepted in.

I suspect Bitcoin-QT won't let me spend unconfirmed outputs though? I know of at least one web-wallet that allows this. I would simply like to use the core-dev client instead, off-line.