interested in replacing FIOS router with Firewalla Gold

I have been a FIOS custoimer for quite awhile although I am not using their wifi. It is pretty weak. Probably because of an old house and thick walls. Instead I am using a mesh network with access points and it is working great. I am interested in replacing my existing FIOS router with the firewalls gold as the primary router coming into my house. According to FIOS support, I should be able to use almost any router since I have cat6 coming from my ONT into the FIOS router which would be a swap with the gold, and then a whole lof of configurations, which brings me to my question.

Is there anyway I can have the gold in my network in parallel so I can configure things like blocked ips, dhcp reservations and port forwarding etc until I get everything properly configured on the gold? It would be a lot easier if I can have their WWW side by side until I get all of the customization done. I would say I am probably above average with the amount of customization I have done with the fios router so migrating from one to the other will be a task.  

Has anyone swapped their fios router with a gold? Thoughts? Suggestions? Caveats?