I have started using forkdelta too. The only thing I make sure before I close the site is to transfer the ETH back to my wallet. I just leave little amounts of altcoins on their wallet.
IMHO the bold part doesn't make you any safer. It can only save you some time in case all interfaces for smart contract stop working. My reasoning follows. If I got something wrong please let me know.
Both etherdelta and forkdelta are just interfaces to the same etherdelta smart contract which has been proven as safe. Now if the new site (forkdelta) turns out to be a scam the attack will be in a form that they try to get your private keys. Same goes for etherdelta, if new owner decides to escape with funds he has to get your private keys. Smart contract is deployed to the ETH network and nobody can change it. They can just stop using it. In that case you can always get your money by interacting directly with the smart contract.
We can only enhance the security by using something like metamask (keeps private keys inside) instead of entering them to ED or FD. Or if you are extra paranoid you can use multiple ETH wallets. At least two, one for main ETH wallet and the other for all the airdrops and small ETH amounts.