OK, 4 moths later, ESXi 6.5 released, and still no reply from Mellanox. As expected, previously working workarounds (uninstalling inbox drivers and installing 1.8.x.x) for SRP/iSER over IPoIB no longer work. I even attempted using 1.9.10.5 ETH drivers with my Connect-X3s and employing iSER, but, still, this didn't work either. Which means I have to stick to ESXi 6.0, possibly, until I decide to EoL my Mellanox hardware altogether.
Mellanox: what's your response to all this? Will there ever be a solution for RDMA storage for VMware, or you just decided it's not worth the effort?