I suggest a single mode VIF for the second level VIF. I believe that if you use multi or LACP Ontap will use both of them. If you want the filer to use one or the other VIF use single mode and favor the one you want.
I believe that LACP should only be used with switches that support that, not sure it would work between two VIFs.
Thanks! I was planning to share the trunk for iscsi, nfs and cifs traffic. However, I heard one Netapp guy saying that doing so could create contention with iscsi and nfs, specially when a storage vmotion is being performed. Is there some truth to that base on your experience?