does anyone know how much bandwidth this consumes? The miner is connecting via RPC to the server several times per minute, isn't it?
Bandwidth is not main concern, but roundtrips/latencies are. I'm working right now on very simple proxy application, which will pre fetch work for few seconds (say 20 sec) to your computer. Then you will point miner to this local application. It will limit roundtrips (as there will be one request per few second) and latencies (miner will not wait to fresh data).