Netgear Nighthawk Mesh Vs Orbi Mesh

I currently have a Netgear D7800 Nighthawk X4S Modem/Router and I want to pretty much expand my wifi into a mesh wifi network. Now I would like to pretty much keep my device and create a mesh system with one of the nighthawk mesh range extenders. So my questions are:

 

1. Are there any performance difference if i were to go to the orbi system (comparing to the RBK40)?

2. would the nighthawk system have the same backhaul as the Orbi ones?

3. which Mesh range extender would be the best to pair with my D7800?

 

One of the main reasons I would like to keep in the nighthawk ecosystem is that my D7800 connects directly to the ADSL line, whereas if i were to go the Orbi route it would pretty much mean i would need my modem in bridge mode and the Orbi main router connected to it. This is a bit of an issue as i have a total of 4 gigabit cables that i need connected to the main router and the Orbi main router only has 3. I would then need to get a gigabit switch for this and thus having to have 3 seperate devices at that one location. Thanks for all the help in advance.