Interesting project. Have you considered partnering up with Quanstamp to audit your contracts? Could be a good one-two combo for ICOs.
Someone asked me the same thing recently and basically, here's my response (from Telegram) as to why we are not using a third-party to audit our smart contracts:
First of all, between us all on the Fabric Token team, we have a lot of programming experience, especially our CTO. And second, our smart contracts include only simple token and crowdsale functionality. These are already well known in the industry and the methods used in them have been audited and used are re-used over and over again. A third-party audit is needed once custom business logic enters the scene. So if a project needs smart contracts for a freelancer website for example, or for a marketplace, then they will have additional smart contracts that are not of the standard token and crowdsale functionality. Then, it is a really good idea to get these smart contracts audited by someone else, capable of doing it right.