Thanks for the info. I have not tried the serrated roughing cutters yet so I'll try and get some to give a go. It some stage I have tried a finishing cut of 0.1mm but I did step down and it did not really make a big difference to surface finish. I'll try 0.35 and full depth.

A few weeks ago I was spot drilling and cutting 25mm thick alu parts for my new machine, it was late and I was tired and I managed to not zero Z after switching tools from a short center drill to a brand new 6mm 2 flute carbide cutter. Hit start, machine went to part 0,0 and from there it ramped into the material on the way to the pocket it was supposed to cut. Sounded like the rumble of the apocalypse and I somehow managed to hit estop before the cutter snapped. I measured it and the accidental slot it cut was +-4cm long and 8mm at it deepest spot. Not a great experience but it has given me a bit of confidence to try slightly more aggressive cutting parameters on my old machine.