I know this is an old thread but I just came across it searching on google for something completely unrelated, so thought I'd share in case anyone else comes across it.

I seem to have found the sweet spot for my machine with a 2.2kw spindle with a stub length, 10mm 3 flute carbide end mill. Small enough that it can be spun somewhere in the powerband, bigger than waiting for a smaller tool to get it all done and can feed at a half decent rate, leaving a lovely finish on the top of 6082. Can get away with taking DOC of about 2mm at 67% engagement. If you have a stiffer machine you'd get away with taking off more.