Fiber leases are usually no different then a standard Co-AX cable modem lease, except most Fiber ONT's have a back-up battery in them that stops them from being power cycled. Here's a little trick to make swapping gaeway hardware easier;
In the routers Internet Setup section you can generate a "synthetic" MAC address to mask the routers actual WAN MAC address. If you always use the SAME ONE, the ISP will be none-the-wiser. Keep it in a notepad doc on your PC and paste it in to that field during initial setup and calling the ISP will be a thing of the past.