Stuart for a mitre saw a negative or at least zero degree rake is a must. Getting into positive degree rake angles means risking hooking into the grain and lifting the board off the saw base and jamming it against the top housing as well as giving a very rough cut going cross grain. Full kerf saw blades will give a better cut. If you use a thin kerf blade I recommend using it with saw blade stiffeners. On a 45 * angle thin kerf blades can wander in the cut bouncing off hard summer grain and digging into soft spring grain. That results in a wavy cut.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.