Right now my wrt54gl is the gateway to the internet and dhcp... I never transferred everything to the 610N because it didn't seem stable unless I could keep it cool and it didn't have dd-wrt at the time.
from the router charts I'm guessing using the wndr3700 as the gateway will make a world of difference than wrt54GL... I also want to set up a VPN server.
I put my wrt54+ddwrt back as the main gateway, because of some issues with the 3700.
You cant use 3700 as vpn server, and it has port mapping issues. I've not been impressed with its stability either.
There has just in the last couple weeks been some releases of ddwrt for the 3700 but they are alpha and reportedly have some wifi issues in comparison to the stock.