XFinity Router - Enable Bridge Mode or Not

> My Xfinity modem/router [...] a replacement at a Verizon store. [...]

   Not a very detailed description of either device.

> [...] This time I decided to not bridge the connection. [...]

   Any reason?

> [...] So I now have two additional wifi connections outside of the
> R9000 firewall. [...]

   Are you using them?  (Are your neighbors?)

> 1) It seems to be working fine

   "It"?  _What_, exactly?

   Cascading multiple routers can cause multiple problems, but,
depending on what you do, you might never notice.  For example, if you
connect one client device (computer, ...) to one router, and another
client device to another router, then communication between those client
devices might fail, but both might still be able to access the Internet.

   For information on a different one-router configuration which would
leave all your wireless-network radios active, visit
http://netgear.com/support , put in your model number, and look
for Documentation.  Get the User Manual.  Look for "Use the Router as a
WiFi Access Point".  For a list of router features which this
method disables, see:

      https://kb.netgear.com/26765/

   As usual, many things are possible.