The logical thing is connect 630b with WAN link to the new device. Easier for any ISP intervention required.
Unless there is an advantage to a late model combined modem/router device?
Edit: I have VDSL.
If the 630b is providing you with all you need then why change. If however you want more features then purhaps consider using the 630b in bridge mode, and purchase an edgerouter or if you are game a Mikrotik. And for wireless look into better solutions like a couple of UniFi or similar devices that are placed strategically in the house to gain better coverage, and a seemless 2.4-5G single SSID
personally i'd resign and get the smart modem. overall the hg630 is actually a pretty solid device, but it's 100mbit ports and 2.4ghz wifi is kinda limiting these days.
Any comments made are personal opinion and do not reflect directly on the position my current or past employers may have.
If you read any of my posts on here you'll find that these "gaming routers" list features that are snakeoil. Killer is one of them. Along with "Tri-Stream AC3200" as you'll never achieve anything past standard Wireless AC speeds (~500Mbit) on this kind of router.
I've had laptops with Killer Wireless / Ethernet and it was really annoying - did nothing to improve anything, it just made things worse. I personally ended up switching out the wireless card in each one of these laptops to one with a standard Intel chipset as it simply performed better.
The price of this router wasn't that bad but to be perfectly honest I would have gone the route that @hio77 suggested and picked up a Spark Smart Router instead. It is a great router, will actually beat this one with performance and could have potentially been of zero cost to you. As I've said multiple times - Netgear, Linksys, Asus have all offered me routers to test with (while asking how I would test them). As soon as they found out I was doing a technical, non-bias test they pulled their offer and have not since contacted me. Every other manufacturer even including D-Link have allowed me to test routers this way and have taken notes when either the router was just garbage (of which I never bothered with a review) or under-performed and solved it by working with me with firmware updates (big kudos to Cambium for this one).
michaelmurfy: The question is what features are you really wanting from OpenWRT that you can’t do on any other router?
mdf: New vulnerability detected in OpenWRT today too: