I wanted to partner with one of the wallet providers that implemented multi-signatory system for my upcoming site coinratecap.com, but I had a second thought about safety of the users, so I decided not to go further with the partnership. Reason is, any cryptocurrency saved on a server is risky. However, is best customers manage their cryptocurrency than to have it saved on the server. Users should have access to their private and public keys. At least, the level of risk involved when managing it yourself is low, rather than when a user wakes one morning only to see that his digital coin has disappeared, it's quite devastating and intolerable. This is one of the major reasons I partnered with shapeshift. Every exchange should consider the safety of every user first before any other thing.