Yes, a multi-sig wallet is more secure. With the multi-sig wallets, even if someone infiltrated Coinbase's offline coins, the hacker STILL would not be able to

Yes, a multi-sig wallet is more secure. With the multi-sig wallets, even if someone infiltrated Coinbase's offline coins, the hacker STILL would not be able to steal the coins. With these new "multi-email" wallets, the hacker would. This is all assuming that the user can manage his two keys better than two email accounts. In fact, the multi-sig wallets were nice too because you could retrieve your coins even in the case where Coinbase went away completely. e.g. if they pulled a Cryptsy or a BTCe