You are missing the bigger potential, to know only answer Matts questions....
Fair enough. It's Saturday, none of my games are on, let's see what comes of this.
Couple of basics from my end. For the point of this discussion, I am ALWAYS talking about Vault Collaboration AEC. The free Vault that comes with all Autocad products as part of their subscription doesn't really work well with Civil 3D beyond basic check in and out. No real sense in it in a Civil 3D workflow. I have no further comment on the subject.
Let's start with a basic question: What problem are you trying to solve? If the answer is purely CAD or C3D related, we can stop the Vault discussion and move on. There are other options as Sinc pointed out, and many of them are simpler to implement. If you're trying to solve bigger business questions: Who modified that file last? What PM approved that file for construction? Does the contractor have the changes we made five minutes ago? Have you sent those revised plans to all 10 of our partners on this project? How do I keep the engineers out of my plat? Those are questions that Vault can help address.
We talk about the Collaboration version because THAT'S the problem we're trying to solve: How do we play well together. VC is designed to work in conjunction with Buzzsaw (which is included with VC as a Subscription benefit, hence my earlier link) to handle the review, release and distribution of data and documents inside and outside the firewall. With VC, you can establish categories of data, assign those categories to specific lifecycles (work in progress, under review, approved for bidding, approved for construction, etc.) and establish security around each of those states based on user permissions. The trifecta of category, state, and user create a security model to insure that the right people in your team always have access to the data they should have access to, and with the proper authority to make changes. Additionally, at any point along the way, you can establish rules for publishing that data outside the firewall to a Buzzsaw site that you control. Using Buzzsaw notifications, Sync, and mobile apps, your partners can have up to the minute design changes in their hands nearly the minute your PM has approved them.
As Michael rightly noted, it's great to talk about the subject. I'm happy to answer specific product questions as best I can.