Catalog Backup strategy

My catalog is starting to get pretty large (450gb) and its becoming a bear to backup and replicate everyday.  Currently i am doing fulls every day and then duplicating to tape.  On weekends i do a full but this one replicates to an offsite appliance and duplicates to tape.  This process is starting to take several hours to complete and i trying to figure out ways of reducing this time. 

I was wondering if its okay to do incrementals of a catalog or if anyone was willing to share some of there strategies with backing up a large catalog.

Thanks.