Guess letting someone 3rd party install your server / compile your server from source requires a bit more than trust. IMHO this will be the key problem for professional /paying users. Those who would just use e.g. an AMI from a repository will certainly have no problem with that.

If you find a way to generate install scripts that can be inspected before those are run or the service is providing the scripts to be run from a local Chef server that might be an interesting approach.