I just trashed my 10 year old Linksys BECFMU10 Modem and WRTGS router (7 years old). Both still working, but had to power cycle several times a week and down load speeds s-l-o-w.
Replaced with Motorola modem Sb6121. Linksys Router e4200v2. After reading a ton of reviews (Best B/Amazon). Works great. Download speeds increased by a factor of 4. Ping 14-20.
Disclaimer...only a week old. So time will tell.
So far my modem has lasted 7 years (when we switched from dialup to high speed).
My modem is docsis 2.0 which continues to be solidly compatible. Comcast are slow to support docsis 3.0. I have looked at upgrading but we get very good speed without it.
Router: I have been forced to upgrade my router because my old routers died.
Wonder if you'll get the same performance out of your new Linksys.