Those cutters are advertised as:

'For ultra high speed machining of high hardened materials.• Suitable for dry cutting and high speed cutting.'

So they're meant for machining hardened steel without coolant at a high speed ... nothing to do with machining aluminium. The coating only helps when the cutter is operating at a high temperature (which is not the case when cutting aluminium), hence the cutter will actually achieve a higher material removal rate without coolant since it allows the coating to reach the higher temperature where it's properties (hardness etc) change and most of the heat goes into the chips.

Quote Originally Posted by Tenson View Post
If chip removal is the key to good finih, then a 2 flute cutter would give a better result than a 4 flute, wouldn't it? It didn't for me.
Yes it will if you use the right feed and speed. The only situation where you might get a better finish with a greater number of flutes is on a finishing pass with limited spindle speed.

Jazz has said it all really - more space for the chips with a single flute and the chips are ejected more readily.

Wait until you've used the 6mm single flute cutters ...