Tape Backup versus Disk to Disk Backup

We are in the process of updating our current network backup system and are looking at either the Exabyte VXA Autoloader or a disk-to-disk solution. Right now we are leaning towards the Exabyte solution. It appears to be much easier to restore data than traditional tape systems. The only hesitation is that we have read that Longhorn will not support tape backup...only disk to disk. Realistically, it will be a probably 3-4 years before we move to the new server platform based on Microsoft's history of releasing products before they are truly ready for market. Does anyone have any experiences either positive or negative related to Exabyte VXA backups?