Orbi Tri Band on wired backhaul

I'm looking at giving this setup a try again. I am wanting to get the tri band 2 pack where I will connect the devices with wired backhawul. I realize the 2nd 5.0Ghz radio is reserved for wireless backhaul but what happens to that 2nd 5.0Ghz radio when a wired backhaul is used? Will my devices then share the two 5.0Ghz radio's over the same SSID like a tri band is supposed to work on a regular router? I'm also wondering the same thing on the Velop so I have that posted in another community forum. I had the RBK50 I believe it was and it got really slow on 1GB conenctions, wired was only giving me about 200MB which I found odd I didn't have any features on that would cause this and it had the latest firmware. Basically my goad is to find the best device that will give me the best speeds on wireless and where the wired conenctions will get what they are supposed to on a gigabit connection.