I don't have it running a machine yet, but I've had an MB2 running with my UC300ETH on my desk, and it's an awesome board.
Here's a Fusion 360 rendering of how I plan to mount the UC300 to the MB2.
The 3 ports used on the UC300ETH line up pretty close with the ports on the MB2, so I'm going to make some custom ribbon cables to keep them as short as possible.
Be aware that both the MB2 and the UC300ETH provide 5V on pin 26 of the ports. CNC Drive wasn't sure if this would damage the UC300ETH, so I cut the pin 26 wire in the ribbon cables I'm using for testing. You can also remove a solder bridge on the MB2 to disable the 5V converter that sends the power to pin 26.
In testing, all of the functions in UCCNC are working fine with the MB2. I've tested Inputs, outputs, the relays, and charge pump, and all work great. When the charge pump is active, it activates a 24V output on the MB2.
UCCNC is starting to grow pretty fast, and they provide excellent support, and their forum is getting pretty active.
I was looking into EdingCNC with their industrial board before I bought the UC300ETH, but it just seemed as little too "different" to me. And I think the UC300ETH/MB2 gives you similar features to Eding's industrial board, for a lot less money.