The 26 valve will work fine with the K valves and might make running a train down the 4% easier if you have a problem with trainline leakage because 26 has maintaining air. Self lapping is a nice feature, but it's not necessary (unless your work force comes from the White Castle burger stand). The thing I like about the 26 air is that you can run it with your foot. That means that you can remain reclined in your LazyBoy and read your favorite magazine! Just what evil of the "old fashioned" air brake system are we attempting to eliminate? If we go too far, you will be left with a cable-operated funicular going over the grade burning tires in the phony smokebox for "effect". Operationally, I like what the D&S did to their brake systems. They kept the "old" automatic and added a straight air S-3 that allows the graduated operation of the air in the car cylinders. (Not that I'm advocating this modification.) I really hate the dumbing down of society. No.6 air and retainers have gotten us this far. Do we really need a "next step"?