Best Configuration for 4 x 1Gb Physical NICs

I have some servers with 4 physical NICs (can't add any unfortunately).  This is ESXi 5.1 with Enterprise Plus. Tr

affic load is very light with less than 20 servers on two hosts.  Storage is exclusively NFS.  No iSCI or FC.  FT is not used.  Here is a diagram of what I'm thinking.  My main questions are -

• Should NFS take two whole NICs all to itself?

• Should NFS load balancing policy be load based teaming?

• Should NFS adapters be active / active?
• Any other problems with this design?

Thanks!