You could try taking a tcpdump of traffic to and from the AMP for an hour of time. This would give you a good idea of the level of traffic that you get in an hour. If you're only using SNMP, you could limit to port 161. If you're doing AMON, you'll have to include port 22 and 8211.
Be sure to attempt a poll now during the capture window from your controller/switches to ensure it's accounting for the data polling activity.