Ah. I was looking in the ESX/ESXi IO HCL from VMWare. So, you won't be calling VMWare for Mellanox support, you'll be calling Mellanox for VMWare support. That means that they will only be compatible with ESX, and not ESXi, since ESXi has no service console, but it sounds like that will suit your needs.
I'm going to stick with the dual-port Intel CX4 cards instead. You think I'll have any problems setuping up MPIO in ESXi though?