Uptime might be an interesting metric. But I think I'd want to know a little about how uptime is related to effective project managment and a project management tool.
Remember, you're trying to show that the technology made a change, so there needs to be some relationship between the thing that you measure (e.g. 'satisfaction' or uptime) and the effectiveness of the technology. I think establishing that link is sometimes the most tricky thing.
Boldalics are mine.