You can actually configure a .koala file in the root of your project to define what to send to Koala.
Nevertheless, I see your point. I'm thinking of going open source and releasing a community edition so you can set-up a hosted version. Would that be interesting for you?
Sweet, I didn't realise that. A self-hosted version would be cool. For my own projects I don't mind sending data, just for corporate work its more difficult. Having something I could run on my own machine and periodically get reports from without having to manually enter time constantly would be really handy.
I'll send you a ping once the self-hosted version is available. In the mean time feel free to send any feedback to martijn@getkoala.co. :)