Since I assume the purpose of these calls is to measure the agent's adherence to the client's standards and, if not, use the shop as a coaching tool, in my opinion--
if the agent did an excellent job and hit all of the marks--it serves no useful purpose to come up "cons", just because we're being asked to. Worse yet, it might even be demoralizing to an excellent agent.
For this reason, if I cannot think of any cons, I will state as much and say something like, "After considerable thought, I was unable to identify anything that would have improved my experience, since the agent created rapport and maintained it throughout the call, clearly provided the information I was seeking and sincerely expressed appreciation at the end of the interaction."
This has always worked for me, however it may have been for a different MSC. Just wondering...are you able to ask your scheduler?
(heart)
I intend to live forever. So far, so good.