All I've ever used is the stewert steel so that's all I can comment on but it has made a new combine out of my 1660. Rumble is almost elimenated with fewer chokeups that are generally easier to clear. I go through a few more rotor belts because of the increased load though but it is worth the trade off. Not to mention the .5-1 mph increase in tough conditions. I would think the afx might be a little better because it looks like there is a more seamless transition into the rotor cage, but I have never run one. I'm sure someone has run both and will post a comparison of the two
I have a Kile on my 1680 and really do like it in all crops I harvest which are wheat, rye, oats corn and milo. I noticed the biggest difference in wheat and rye. I'm like robmgrig you will gain .5 to 1.0 mph. One of the other things I like about the Kile is all you do is take the elephant ears off and bolt the Kile on. They are very simple to install.
I beieve the first box of Kile product is allready in Aus. But you might confirm that with Ron Kile himself.
IMO, the Kile front is the best design.
That 45 degree angle that he retained for the wear blade helps not only to make the flight stronger, but also gathers the material and gets it moving in the circular motion much faster than an edge of a 5/8" flight. In other words, that 45 wear blade acts both as a paddle to remove the material from the feederhouse exit quicker while moving it rearward, but it also is a more rigid design that helps reduce the forward flex of the flights so one can set a sharpened wear blade closer to the kidney.
That's my opinion, and I'm stick'n to it.
Is it? I think it depends on your cropping. A lot of folks dont seem to have any issues with the deere or other brand designs. In my area, the feed accellerator, or whatever its called, is the hangup. It pluggs and wraps in long, viney, tangled crop matter. It is a horsepower sponge with no real benefit.