Connecting class-compliant MIDI interfaces?

[Lizard of Oz]

There's tons of inexpensive class-compliant MIDI interfaces with multiple inputs and outputs (e.g. the Nektar MIDIFLEX4, Miditech MIDIface 2x2 / 4x4 / 8x8, ESI M4U eX and M8U eX), which could be used to add MIDI DIN ports via the USB hub. 

I found nothing in the Compatibility Tracker, has anyone successfully tried any of those with the MRCC?

[Jesse Johannesen]

So the USB host port are 4 in 1 out, so while it may work to some degree to plug and play a device with more, they would still be limited to the 4 in 1 out limitation and I can't guarantee they'll get numbered as expected. It's definitely worth a shot if you have one near at hand.
We're in the process of releasing a 4 in 1 out MIDI interface that will be a perfect fit for the purpose, as well as working as a MIDI interface for your computer or a 4 in 1 out Merger standalone. They should be available in the next month or two.

[Lizard of Oz]

So the USB host port are 4 in 1 out, so while it may work to some degree to plug and play a device with more, they would still be limited to the 4 in 1 out limitation and I can't guarantee they'll get numbered as expected. It's definitely worth a shot if you have one near at hand.
We're in the process of releasing a 4 in 1 out MIDI interface that will be a perfect fit for the purpose, as well as working as a MIDI interface for your computer or a 4 in 1 out Merger standalone. They should be available in the next month or two.

What is the reason for the limitation to one output per USB host port?

Edit: I am aware of the XPANDR 4x1, but I'm afraid that this would not be of any use to me as a midi interface, one output kind of defeats the purpose for my usecase.