The Bitcoin people say that you should create a new address for every transaction. Even if you don't care about your privacy, it protects the privacy of the people you are trading with. In our case, sending to the same address links those transactions. So if you fuck up once, for example by sending directly from MtGox to your SR address, then the other deposits can be linked to you, and those transactions could be traced to accounts on other services. Realistically it's probably not a big deal, because LE is unlikely to be going after small time buyers. If you are a vendor, then you should definitely withdraw to a different address each time. I also wonder if it taxes the SR server too much. I've never operated a wallet with tens of thousands, or perhaps hundreds of thousands of private keys.