I'd absolutely try as much of your own equipment as possible. Comcast may well be up to other tricks, but they also have no incentive to give you anything other than a "good enough for most people" modem/router.
It can be surprising how much of a difference better networking gear can make. I've seen a VoIP router throttle a 50 Mbps to 5 Mbps for no apparent reason (over-aggressive QoS logic?). I've also seen issues with modems that don't have the latest-and-greatest DOCSIS support (you'd think Comcast would notice that sort of thing when you complained, but...).
I'd also avoid combined modem/wireless router boxes (which it sounds like you have) like the plague. The bundled wireless is usually much worse than what you can get separately. Plus wireless technology tends to move faster than modem technology anyway.
It can be surprising how much of a difference better networking gear can make. I've seen a VoIP router throttle a 50 Mbps to 5 Mbps for no apparent reason (over-aggressive QoS logic?). I've also seen issues with modems that don't have the latest-and-greatest DOCSIS support (you'd think Comcast would notice that sort of thing when you complained, but...).
I'd also avoid combined modem/wireless router boxes (which it sounds like you have) like the plague. The bundled wireless is usually much worse than what you can get separately. Plus wireless technology tends to move faster than modem technology anyway.