What would a better method be?
I thought that when you transfer btc to and from a web wallet, such as blockchain.info, the coins that get transferred out are not really the same ones you put in. They are a random bunch of coins from the pool which blockchain.info is holding ofr its users.
Wouldn't that mean that the coins coming from bc.info A and B would not be related to the original localbtc wallet as they are not actually coins that came from there.
AFAIK when you use blockchain.info as your wallet then you use your own addresses and thus the btc are never in a pool where they could get mixed and distributed differently.
You might want to try Mt. Gox.
But you will have to pay withdrawal fees.