So those are my reasons.
Buy it, unplug your existing modem, plug the new one in, and call Comcast. I had mine out of the box and up and running in all of 15 minutes (most of that was spent on hold and waiting for the modem to reboot).
The only thing I've ever needed was the serial numbers and such that are printed on the bottom of my modem.
Pro tip, the chat is much faster, tether to your phone for internet and do it via their web chat.
To that end, I've done the modem switch probably a dozen times for myself, family, or friends and I've never encountered any resistance from Comcast during the process. Though they did fat finger a MAC address or serial number one time.
To configure it, you just plug it in. I think you may have to call them after you plugged it in and then activate it on their end.
You can figure this sort of thing out with less than 1 hour of effort.
Today, from that list, I'd buy the Woot SB6183 ($51.09 on Amazon-ASIN B018IS1S4C) as that's what I've been running at home for 13 months without issue. (I upgrade about every 6-9 years. You caught me "just" after the latest one.)
It's a 16x4 modem, though when I use it on Comcast, Comcast operates it as a 16x3 (16 channels down, 3 channels up)
I still prefer to avoid combo modems though, I find that the Wi-fi tech upgrades at a faster pace, and prefer to keep the devices separate rather than combined into one box. YMMV, do what makes sense for your setup.
When I'm right under it, I can get 400Mbps u/d from my iPhone and my laptops. In the worse location in the house I get 120/120. My house is wired for gig-e throughout but I with that kind of wireless speed, I didn't bother about getting the more expensive Roku boxes with 10/100 Ethernet connections.
Of course I usually get 900+ u/d wired.
I've done this multiple times over the years and saved a bundle.
Why by expensive routers, repeaters, etc when you can get a TP-Link for $20 that lasts for years and if it breaks... you spend another $20 to get the newest version... AND you've still spent less than the alternatives?
I do spend the extra where warranted... but TP-Link is top notch "crap" in my book.
That all being said, my entire home network is Ubiquiti. So we don't disagree on which is better of the two brands.
What would you suggest instead?
For about $70 (about 5mos of rental charges) you can get a Surfboard barebones Docsis 3 modem that will vastly outperform whatever junk they rent out.
After that you could get a TP-Link Archer C7 for sub $80 that will have good range and performance for that price point.
So within about the first year you've broken even with vastly superior components and you'll be able to take them with you to any cable provider you wind up using in the future.
I get why most people don't do this, they don't even know it's possible, but I'm amazed when colleagues in the industry are still running the company hardware.