The web GUI works without issues.
I specifically bought the AVB because I trusted IP-over-RJ45 (the Ultralite AVB has its own RJ45) more than IP-iver-USB, which would be true of (say) the Ultralite MK4.
My impression was that either way, each device must end up with its own IP address, and you just point the browser at the one you want to talk to. I don't know much about how IP-over-USB works.
Note that if you have two devices, you're probably better off linking them over AVB. I have the vague impression that they will show up as a single device in the web GUI (but I'm not really clear on that).