Cfengine 3 Community Addition promies Convergent reporting

[jab2805]

I have been trying to introduce cfengine in my environment of around 1k servers and global in scope. An issue I have is reporting. Its hard to obtain clear reports of how convergent a class of server is. For example, I would like a report that class x is 80% convergent. I understand this is done in the commercial version however, has any one done this level of reporting in the community version? Some ideas I have are:

1. Parse the output from cfagent -IKv and put it in a database. The problem
with this is it's resource intensive.

2. Rewrite all my promises to report when every they are executed.

3. Send an email for every change then mine the data for the info.

Thanks