I'd say that a circular saw with a fine tooth blade would be a better choice of tool - routers are OK for trimming, but very slow for cutting, even if you have a heavy 1/2in router. In terms of the material itself the absolute best type of cutter to use on MFC (melamine faced chipboard) is the replaceable tip TCT type. That's because all chipboard contains a percentage of recycled materials which in turn may mean the occasional small screw, piece of meal, or even pieces of grit are all possibilities. Hitting one of those with a carbide tip will potentially chip or blunt it. Replaceable TC is therefore a simpler and more cost effective solution if you are doing a lot of material - it's also sharper than brazed carbide, but at a heck of a premium in price. On the other hand solid carbide spiral cutters, whilst offering a far smoother cut are very susceptible to damage and expensive to regrind, so they're not really a good idea on chipboard. For lower volume the only sane choice has to be ordinary brazed carbide. Size? The bigger the better, within reason. I often route MDF, MFC and MF-MDF with 19 or 20mm diameter cutters on 1/2in shanks because the heat-up more slowly (lessening scorching), the extra mass means that they slow down less under load, and the scallop patterns on edges are far less noticeable - but they do need a big router (1/2in 1800 watts and up) for effective use - you aren't going to run one of them on an 8mm plunge router. One thing which helps get a smooth cut is using dust extraction on the router, ideally from blow the base
