VEAgent backups are great for virtual environments, but restores can be a nightmare. In my 12 years of experience with Data Protector I have not seen a fully working VMWare GRE. In the past we mostly avoided it due to the extra cost, but now with the capacity based licenses I've tried to set it up and it is... horrible to say the least. Especially compared to Veeam.
While trying to figure out what shares should be necessary for a successful GRE and given the fact that VIX seems to unsupported for vCenters 6.5 and above, I was wondering if a DP disk agent would be a good idea for a GRE restore - 5565 is already allowed in the network between cell/media servers and clients. No additional accounts would be required and generally it should not be a problem to deploy DP in the entire environment, even if VEAgent is used for VM backups.