Surely when you unplug the old router, the devices connected would not / cannot stay connected.
When you plug in the new router. On the devices connected, you'll have to either a) reconnect them to the new wifi network or if using ethernet do nothing.
The new IP will be resolved via DHCP server. It wont hold onto the old ip unless it's set as a static IP?
The only issue I COULD see, is the modem might not recognise the new routers MAC address and require a reboot to provide internet access via the new router - although in reality I've not seen this occur.
I guess a fresh restart will resolve some issues that COULD but possibly should not occur. Whether it is necessary, I'd argue not.
Edited by ukhardy07 (Fri 18-Nov-11 16:25:15)