I’ve done so, but didn’t notice much of a difference.  All depends on the layout of the building, wall materials, and if you have multiple levels.  I have my satellite in line of sight of the primary and it gets about the same speeds wired as wireless.  
 

I have to say though, in my personal opinion, if you have a way to wire it up, wiring would be a better route for anything network related.

I don’t think it matters if it is wired.  The main talks to the satellite over the wireless backhaul.  Basically all you would be doing is making you satellite a switch for other wired components.

It depends on your setup.  You will be capped at 1 Gbps with Ethernet connection.  The BackHaul connection (Wi-Fi connection between the mAX main and satellite) can achieve up to 4.8 Gbps. 

You can check the SURFboard Central app to determine the BackHaul speed of your current setup and determine if the Ethernet connection is better for you.

I’m a fan of wired backhauls. I’ve always used them when I have a chance. Less latency, better stability, and it less wireless congestion if there’s other devices in the area using the same spectrum as the backhaul.