Re: How much time would you need to invest?
Sorry, poor choice of technology. It's precisely the issue of reconfiguring the router to marry up with the existing network configuration that's the pain. That includes re-establishing the DHCP settings: the last couple of routers I've been supplied don't allow you to directly input fixed MAC to IP mappings, you have to issue a DHCP request from the client, have a dynamic address allocated, then when the router has discovered the device configure a fixed IP address, then issue a further DHCP request to get it. I have quite a few devices with fixed addresses and it's a pain to go round them all. WiFi passwords aren't the problem.
Yes, I should probably run my own DHCP server, but, inertia, etc...