Yes, I would like guest mode and additional Ethernet ports which the XB6 does not support.
The XB6 hardware supports secondary Wi-Fi networks so it's technically possible for Comcast to add support for Guest Wi-Fi Networks at a later date. Until then, I would buy an inexpensive access point (something like this) for temporary guest access.
As for additional Ethernet ports, you get an unmanaged Gigabit Ethernet switch in the $15 to $25 range. I have even heard of the Rogers install techs providing one free of charge, if required.
You can add either of the above pieces of hardware without impacting the supportability of the Rogers-supplied hardware, and they would be less expensive than a high-powered router that would be required to replace the functionality of the XB6.
@jj59 For what it's worth, I also have my XB6 in bridge mode and am using my own router, which runs OpenWrt. No issues. For Wi-Fi, I've tested with a Linksys Velop mesh, various different access points, and have also tested with the Xi6 set-top boxes connected wired.
If I should ever need to call into Rogers tech support, I have my network set up in such a way that I can easily disable Bridge Mode on the XB6 and connect the Xi6 set-top boxes to the gateway with wired Ethernet through a switch.