I’m not a big fan of all-in-one designs. Sure, it’s probably just paranoia, but I have a netgear hardware firewall behind my DSL “modem”, and my wifi AP connects in to that. If you need the deskspace, just hang ‘em on the wall, put a frame around it all and call it art. :-)
I’m still kind of unsure myself, but the price difference is very little more to get the total upgrade. Plus I won’t have to spend time getting different brands of equipment to work together.