go with hot catalog backups and set the cold to user initiated only. I was having all kinds of problems, loosing connectivity to my libraries, loosing connectivity to the EMM database, ect.. I switched to hot backups and have not had one of those old problems since.
The thing to keep in mind with Netbackup is when a cold catalog backup is taking place the emm database is locked. So much of your functionality is lost. If you try and perform a function that requires access to the emm database netbackup can end up in an unknown status.
Support recommended that I go with Hot backups. So now my catalog schedule does weekly inc, weekend fulls and monlhly archive just like my other backups. I send the catalog backup monthly archive offsite with the other tapes along with a copy of the email that is sent. With this a full recovery is possible even if the datacenter is lost all you need to do is recall the monthly archive.