I'm a little unclear what you're trying to achieve here. Usually we recommend storage design discussions go through the account team, even for existing setups. They aren't just there to sell you stuff, but also help set it up and bring in architects as needed, etc. They help you ensure you get the best out of your existing purchase too.
Regarding which protocol to use, IIRC NFSv4.1 on ESX is still kinda new. I heard in the most recent ESX builds it's gotten a lot better, but NFSv3 is still probably the most stable, or iSCSI/FCP. What are you needing exactly, and why are you wanting to change?