@Gonzodog 

I would use different SSIDs, it is nice to have only one network to connect to, but them being seperate network devices can give some issues. Mainly the one being that the client does not realize what it is near so you may have a situation where  you are physically close to one AP, but it is still connected to the further AP giving the impression the closest AP is bad or not working. Having different names makes it obvious what network you are in fact connecting to.

@Tony   

Thanks.  I ended up switching out my AX10 router with the C9 (and a C900) and got pretty much the same speed on the 5GHZ and 2.4GHZ, when the routers are connected directly to the modem.  So, apparently my decrease in 2.4GHZ speed is most likely due to the amount of devices I have in my house (~45 devices).  I figured I will stick with my AX10 as the primary, since that is the newest. 

With the C9 as the AP (wired), my 5 GHZ speed on that device is about half (50 MBps instead of 100).  Not awful, but not quite the same.  I'm now thinking about buying another AX10, using it as the AP, and hoping that between the 2 AX10s I should have enough coverage throughout my house.   Thoughts?  Is the AX10 as AP just as good as a dedicated AP device?  For the price, the AX10 is cheaper than other AX range extenders and gives me redundancy, in the event I ever needed it.