Clarification needed with P3400, SAN iq 9, multisite and vmware 4.1

[Ryan Nelson_3]

We purchased a P4300 last year as our first iSCSI san and it’s been great. We just purchased 2 more starter SAN's for expansion, bringing the total to 6 nodes. We have two primary sites, both with vMware ESXi as the primary OS that will be connected to the SAN(s). The "old" 2-node SAN is 8.5, new is 9.0, all the servers are G2 hardware.

The first thing I'm looking for clarification on is how multi-site SAN, MPIO and ESXi interact. I know ESXi can't separately route pNICs assigned to storage. Doesn't a storage VIP in each site, with servers assigned to their respective SAN sites, direct all the traffic where it needs to go? If so, is it still possible to achieve MPIO?

In multisite with multiple VIP's, is it possible to keep one location up if the link is severed? The documentation seems to indicate a primary can be assigned if desired. If its not necessary, what happens? Does a 3rd site FOM choose the site that stays up, or with the correct number of managers at each site, does everything stay online?

All that aside, is it best to just configure two clusters of three nodes and for any replication just manage remote snapshots?

Thanks in advance!