Hi Joel
if the Internet is critical for the business then for sure you need some redundancy and high availability to your Internet service
by having another Internet link from different ISP using additional router you will make sure that if the first router or ISP has any issues the Internet will be reachable by the users using the second one
also you can have loadbalncing or loadsharing using both routers and Internet link in the case both of them are working and each one will back the other
but keep in mind that if you have one firewall the this firewall will be your single point of failure as if this FW fail then you will loose connectivity to your edge routers ! you might consider having another firewall to work in active/standby mode with the current one
HTH
if helpful Rate
