Is there any merit in using the VDR disk milage/usage as a guide for selecting which sized VDP appliance to deploy when it comes to restore points retentions & number of VM's backed up?
Is the dedup technology more efficient in VDP than it was in VDR or not suitable for a direct comparsion between the old VDR 2.x and the new VDP ?
Does not having to have 2x500GB destinations as in VDR mean that extra space can be gained from having more similar vm's deduping into the same store
The safe bet is to pick the 2TB VDP appliance if you foresee that your backup can grow quicker.
Deploy the appliance with thin provisioned disk type, in that way you are not wasting any disk space upfront.
But one thing for sure is VDP promises much better de-dupe than VDR