It depends upon how much detail you want CS-MARS to know about the events being sent from the device. It is usually sufficient to set reporting to a mid-level and then monitor the data received by the CS-MARS. If you feel you are not getting enough detail, increase the level. If you feel you are getting too much detail, decrease the level. (You may also want to decrease the level if you have a large number of 'Unknown device event type' messages as these indicate received messages that CS-MARS cannot parse).
For firewalls, the configuration guide mentions setting the level to debug to allow very granular querying on event data. This is covered here:
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...