One thing about the trezor that worries me. Say you transfer your btc there and put the trezor away for a decade+ in a safe or something. What happens if in the future USB ports become obsolete and we can't plug them in to any new computers with new hardware?
That is why I use bitcoinarmory and a paper wallet. You can also back up to a usb stick and put it in your safe along with your paper wallet. Then create a watch-only wallet, wipe armory's user directory, install the watch only wallet (which is write only) and then you have true security. If you every want to spend from your offline wallet, use the mobile app mycelium to access offline BTC.