Currently have my cold setup offline in Bitcoin-QT. Downloading the blockchain from zero is rough. It's time to update. Can I create a similar cold storage solution with Multibit? Will this speed up load time when I bring coins online thru Multibit? Are there any other benefits or weaknesses that you can think of with a Bitcoin-QT cold solution vs. a Multibit cold solution?
MultiBit cannot do true cold storage where your transactions are signed offline and then you transport them to a different machine and broadcast them.
The underlying library, bitcoinj, does support it but it is not in the user interface.
If the size of the blockchain is the main factor, Electrum might be worth looking into. I am pretty sure you can sign a transaction, move it and broadcast it on a different machine. I think this is done on a command line.
It is still several months away but a nice solution will be Trezor where the signing is done on a hardware device and the host machine is used to broadcast it. I believe all of MultiBit, Electrum and Armory are planning to support Trezor.