WiFi Setup Advice for Max Speeds

What kind of speeds do you currently see?

I have Xfinity Gig, which is advertised as 960 down / 40 up.
The Orbi itself has a maximum of 866 Mbps (5 GHz, 802.11ac) for client devices, with about 1.7 Gbps dedicated for backhaul traffic betwen the base router and satellites.
Futhermore, maximum speeds you see may be limited by the actual client devices you happen to be using and the type of WiFi adapter they happen to use.

In real-life speed tests using my 2015 Macbook, I consistently see ~550 Mbps down, and ~40 Mbps up while connected to my Orbi satellite.

With that said, FiOS is advertised as 940 down / 880 up. I expect you would see better upload speeds than I do, but download (depending on your client device) should be roughly in the same ballpark. If you have a new/faster client device than I'm using, you migh see somewhat better download speeds, perhaps.

Hope that gives you a rough idea of what you could expect.