E-CAD software as a service

E-CAD seems like a perfect application for the concept of "software as a service." There's tons of data to be stored, the data needs to be accessed by multiple users, there has to be tight version control, and nothing has to happen in real time. The software itself is very complex and requires frequent updates, so this also seems to fit the software-as-a-service model. Does anyone have experiences they can share about E-CAD software as a service?