You'd normally choose one storage environment and set up your storage networking for that protocol. Why would you use both in the same environment?
Since you use a five disk NAS, the chance that your network will be the bottleneck is slim. Spindle speed is a more likely limit.
Than again, to measure is to know.
I use NFS at home so I can easily move and/or modify the VMs. The three SATA disks are for bulk data only. The lab VMs are on an SSD.
DS411 (3x 2TB RAID5, 1x 128GB SSD), 2x HP Microserver ESXi 5.0