@Headroom: I experimented with a similar configuration (I forgot the brand of that little router) and it worked great, except for the form factor; we want to embed the entire thing in a couple of (230V) AC outlets (and then some); two small shields stacked on top of eachother would be ideal; an additional router would become too large (I'm just responsible for the software, so don't shoot me, aim for the hardware guy 
kind regards,
Jos