Currently, you can capture & report on how many ideas are received [within a specified time frame]. It would also be helpful if we could capture & report on how many public comments are received [within a specified time frame].
It can be difficult to secure the needed resources to successfully manage an idea portal. This is often based on your ability to accurately demonstrate your workload. Until Aha! captures client comments & reports on this data like they do Ideas, there's no way to account for the time spent responding to clients.