What are you asking exactly?
Is it okay to run NFS and iSCSI on the same vif? Yes it sure is.
Would I do this? Probably, however as I like to use jumbo frames for iSCSI and normal frames for NFS I might possible use different VIFs for iSCSI and NFS traffic. Everyone's enviornment is different, so this might not work for you.
Is NFS better than iSCSI? Depends on what you're trying to achieve, for VMware workloads; absolutely!