Hello Alexis.
Why use all those physical NICs and not simplify with fewer NICs and cabling.
Things like Management, Migration and Display you may put on the same set of NICs (bond0) as Management and Display traffic are marginal so you have an almost dedicated NICs for Migration traffic.
Then yes is good to separate VMs traffic and iSCSI in different set of NICs.
If you really want to use all your physical NICs add the one left in this scenario to either add more bandwidth to VMs traffic or to user as active/backup if you have two non-stackable switches, either with bonding too.