Is that true even if you only spend some of coins and not all the coins? I seem to remember there being something very tricky about this if you are using a paper wallet.
What is considered risky is spending only a fraction of the paper wallet, for the following reasons:
- you just used the private key for creating a transaction, so the chances of it being compromised increases
- the client you used might have sent the change to another address while you're thinking the remaining coins are still in the paper wallet
But if it's done well, yes, it's possible to spend a fraction of a paper wallet.