I personally would not get rid of the backup software. I used Net Apps in the past which stored only file data and it would take a snap shot of all the data every 4 hours. The restores using the Snap shot feature was extremely quick, however, in the event of a total system crash, you will need to restore from tape.
I would continue to do nightly backups of all data using the backup software of choice (i.e. Veritas). Example backup method would be Monday thru Saturday Incremental backup job and Sunday Full backup job of all data. This will provide you with redundancy and you want have that single point of failure of relying on the snap shots.
Additionally, you cannot retain the snap shot data for long period of time (example 6 months) on the snap shot location due to growth of the data. Using the backup software you can continue to backup data to tape and store the tapes offsite or locally for disaster recovery purposes.