i have been using 3 flute ma ford aluminum cutting 3 flute carbide endmills for a while now. i use a 1/4", 3/8" and 1/2". i love them.
i need to go back and look for my actual feed for the 1/2" endmill in 6061-t6, but i believe it was 30 ipm. i know i was running 4500 rpm with the 1/2" cutter, .1" depth, full cutter width that was working great. it is kind of cool when there is almost no sound from the cutter and all you hear is the rooster tail of chips hitting the tins on the machine.
i may have to try the atrax 3 flute endmills. they are much cheaper than the ma fords. i'd like to hear how the atrax 3 flutes work for you once you get a chance to try them.