Thanks for the security hardware explanation, PING! Am thinking of going with an alpha-numeric passcode....even tho. it is a PITA when I reboot the phone (I just use TouchID for normal unlocks).
Keep using the TouchID. However, if you are required to turn over your iPhone under any kind of a search warrant or arrest situation, make sure you turn it off. On restart it will require the passcode before your fingerprint will work again. While they could, conceivably, FORCE you to use your fingerprint, they cannot force you to remember or enter your passcode.