I changed modems due to greater security. I am confident that the modem has a greater level of security. I also read that a separate modem and router would be an improvement over a gateway. A gateway has been defined as a modem and router.
My CM1200 is about 100 feet distance from my R8000 router passing the signal through 6 walls 1 A/CHV unit . My Spectrum internet is at 400g. I get 358 speeds 3000 feet down the road through aluminum siding. I have a 1 mile plus circumference with my house in the center I can logon to my wifi at 200Mbps . Let alone in every nook and cranny of my 2400 scft house. Speed and distance like a .22-250 on a gopher hunt.