Thanks etotheipi, but this still doesn't totally satisfy my question. Let's say a user has an old QT wallet from many months ago with some coins still on it. The user has never given the private key to anyone, & wishes to take those coins from the QT wallet and keep them safer in an armory offline wallet.
Does sweeping or importing do this instantaneously off-chain so there is no transaction fee involved? Or more directly, how exactly do these mechanics work? Let's also assume the user wishes to migrate entirely to the armory online/offline way of keeping their coins, so that original QT wallet (or blockchain or whatever) is in no danger of ever being used again to either send or receive.
I'm trying to figure out the financial benefit (if any) of import/sweep versus simply sending a normal transaction over the network for the entire balance to armory wallet.
Also, I've read countless times that address re-use is strongly discouraged. IE: you want to use an address once to receive, and once to send, and that's final. All transaction change goes to a newly created address. Is there any SECURITY reason for this? Or is it simply a privacy thing? For instance, I believe just-dice has an offline wallet that gets constantly reused. According to blockchain tags, it's this:
https://blockchain.info/address/14o7zMMUJkG6De24r3JkJ6USgChq7iWF86Is that a "Very Bad Thing"? What are the security ramifications to operating this way? Assume they're set up to use armory.