There have been attempts at Bitcoin banks/vaults before and they all got hacked. BitGo's isn't a Bitcoin bank, but its multisig technology was mean't to provide 100% security for Bitfinex's funds. Although I have not yet read an explanation of how it was done Bitfinex's coins were stolen despite BitGo's technology.

I wouldn't trust a Bitcoin vault's technology to secure my funds any more than I would trust BitGo's technology.