My two cents... It depends on a lot of things. Are you having any issues with the C9 or at or near its limits? Do you need any of the extra features the AX50 has that the C9 does not have? What kind of speeds do you have from your ISP? The main difference is one is AX and the other other is AC. Looking at the specs, the 2.4 WIFI is slightly slower on the AX, but a lot faster on the 5Ghz AX, I don't think you will see much difference even if you have a Gigabit ISP speeds as your limit will always be the slowest link which would be your non-AX devices. To get the speed benefits of an AX router, you need AX devices. So with what little I know about your set-up and needs, I would not make a change at this time as I would not expect much if any improvement speed wise which seems to be your concern. See this for more info https://www.duckware.com/tech/wifi-in-the-us.html (you can skip down to section 16 and 17)