If a service agent user is cc'd on an incident or service request will they receive private comments?
Unfortunately, no. Anyone CCed act like the Requester, so Private Comments wouldn't be emailed to anyone CCed, even if they're an agent.
Hopefully improvements to the notification system in the future will help make this more granular. Feel free to voice your thoughts there:
If you have other agents you want to be brought into an incident but don't want to have the discussion in public, see my post:
Reassigning incidents between groups and notification problems
Retrieving data ...