if you're on newest wallet (as of may 25 i believe) all you should need to do is dump your privkeys as per the writeup above, record them, close client and swap in a backup wallet.. upon re-opening client you will see 0 balance as if new wallet, import your privkeys each one takes some cpu time to get loaded but worked great for me.

dont expect incorrectly gained stake to show up but you will have your intended stake included nicely as well as untransferred legit coins

i did not have to download any new blockchain, downgrade client or clear any maps.