I do. We have 6 nodes of P4300's, G1 & G2. Ours are setup with their stock 2 1Gbit NICs in ALB mode.
Here's the key: In LeftHand, every volume has one node assigned to it that acts as the "gateway" for its I/O into the ESXi host.
You point all of your ESXi hosts at the LeftHand Virtual IP address and then the SAN manager will handle load balancing which node serves up which volume. You can then do round robin iSCSI connections on the vSphere side to get multiple NICs talking to the LeftHand.
You get more traffic I/O by having both multiple nodes AND having your VMs split across multiple volumes so that you don't have all of the traffic going to one SAN node.
It's a silly limitation IMHO...because if you were to take that same SAN...send it directly to Windows Server using iSCSI using the HP DSM for MPIO, then you would get TRUE MPIO out of it. That doesn't exist for vSphere. 