@Julien: You are right, but here there are two egress vmnics per vswitch. I guess,the above will apply only when you have one vmnic per vmk. ESXi will select only one path of the two. To make use of both the vmnics you need to configure port binding.
In a VMware vSphere® environment, the default iSCSI configuration for VMware® ESXi™ servers creates only one path from the software iSCSI adapter (vmhba) to each iSCSI target. To enable failover at the path level and to load-balance I/O traffic between paths, the administrator must configure port binding to create multiple paths between the software iSCSI adapters on ESXi servers and the storage array.
Without port binding, all iSCSI LUNs will be detected using a single path per target. By default, ESX will use only one vmknic as egress port to connect to each target, and you will be unable to use path failover or to load-balance I/O between different paths to the iSCSI LUNs. This is true even if you have configured network adapter teaming using more than one uplink for the VMkernel port group used for iSCSI. In case of simple network adapter teaming, traffic will be redirected at the network layer to the second network adapter during connectivity failure through the first network card, but failover at the path level will not be possible, nor will load balancing between multiple paths