I see a number of different things being discussed here, because "mom type" is ambiguous. The general cases I see discussed so far are:
1) the "standard" pbs_mom
2) the cpuset pbs_mom
3) the "Cray" pbs_mom
4) pbs_mom using the cgroups hook
Only the cpuset mom is actually a "special" pbs_mom binary. The "Cray" mom is in actuality an otherwise standard pbs_mom that has $alps_client set in her config file. A pbs_mom using cgroups is of course just a standard pbs_mom using a specific hook.
Maybe the most useful thing here is for pbs_mom to dump the contents of her config file to the log upon log open/HUP, and also list all hook names, enabled, user, and event attributes after the server and mom have made contact (since what is available to the mom at literal daemon startup/log open time may not actually be correct)?
That DOES NOT cover the cpuset case, but as has already been covered, the plan is for the cpuset case to go away eventually and I believe we would actively avoid any new "special binary" feature implementation analogous to a special binary like pbs_mom.cpuset. Adding special code and a new log message interface specific to the cpuset mom case does not make sense to me at this point in time.