A couple of things I'd like to suggest:

1) rather than ratings between -10 and +10 why not just keep it minimal so: -1 (failed), 0 (resolved) or +1 (succeeded)

2) reserve the entire 8 digits of each protocol tx so that the protocol can be extended

and of course it would be advised to *formalise* the protocol *before* starting up the service.

Apart from rating specific transactions for services or goods it would be useful to have *special* ratings for things like GPG identity and perhaps even other *real identity verifications* that could useful for services such as loans.