as long as you dont have multiple syslog servers defined, in general you should be ok to turn on whatever debug you like in most cases. Just check the CPU load after you have enabled all your debug and try to use a more narrow debug mask like "logging level debugging system process snmp" etc.
As an asside, I have seen one case where user+security debug logs were turned on plus there were 4 syslog servers defined. This drove the syslog process CPU high and caused some impact to ipsec setup times.
Having said that, the SNMP debug is not particularly useful on the controller for troubleshooting connectivity issues etc. rather its more debugging about how the various applications populate the mibs during a snmp request.
regards
-jeff