I'm also using a 30degree carbide tool for etching pcb's on FR4 - the feed rate I use is significantly higher than indicated in John Ferguson's post. Currently set to 500mm/min (20"/min) with a spindle speed of 18,000rpm, results are immaculate - clean edges to all traces and smooth bottoms on the isolation cuts.
Stock flatness is assured by a home made vacuum table with MDF surface machined flat in situ - checks out on a dial indicator to better than .0005" over the whole of an 8" x 4" area. Traces and isolation down to 0.008" can be achieved provided router backlash is properly compensated.
Machine is a Stepcraft SC420/2 with a StoneyCNC industrial grade VFD spindle. Control software is UCCNC with U100 parallel interface into the router. The computer is a Dell 610 running Win XP - dont need anything more fancy than that.