Should I import my secret recovery phrase from MetaMask in ZERO?

No. While it is possible to import your MetaMask seed phrase in ZERO, this will provide no extra security at all. 

MetaMask is a so-called ‘hot’ wallet: the key is generated and stored in a browser or app that is connected to the internet. On the ZERO, the private key is generated by a unique procedure and stored 100% offline using hardware made for this purpose.

To use the MetaMask integration you should sync your ZERO with an existing MetaMask wallet. Then your ZERO accounts will be available in MetaMask. See Synchronize ZERO and MetaMask.

So, next to the backup of your ZERO wallet, you will now also have a backup of your Metamask 12 word seed phrase. This MetaMask seed phrase will not give access to your ZERO accounts. If you would recover the MetaMask wallet, you would need to sync with ZERO again.