Are 2 10Gb Nics enough?

I am working on a datacenter project that is going from FC to NFS storage (NetApp). The blades the customer is looking at have 2 10Gb ports. I have requested an additional 2 ports via mezzanie card but have been denied because of cost. I have not setup an environment using NFS before so I wanted to put it out to the community....

Will 2 10Gb nics with NIOC enabled be sufficient.

(P.S. I know this comes with the answer "well it depends" but looking more for input from someone who has deployed this before or seen the need for more than 2 10Gb ports.)

Thanks!