How paranoid should you be when storing cryptocurrencies?
1. I am currently storing some BTC and LTC at paper wallets, but this does not feel good because what if the paper wallet gets 100 transactions in? Won't the paper wallet then be "full"? What if I accidentaly missed one character when I copied the private key by hand?
2. What if I import the private key to my Bitcoin-QT wallet on my computer in order to spend some BTC. When I am done spending the BTC I backup the wallet.dat on a USB stick, then I remove the wallet.dat file from the computer. The file will still be on the HDD and what if someone gets their hand on my computer and runs some recovery program that recovers the wallet.dat file?
I have soon 10 000€ stored in cryptocurrencies and losing them would suck so hard. What if someone comes up with a backdoor in Windows that steals everyone's wallet.dat file? I am sure there are people working on something like this, since they would be millionares if they succeed...