I probably shouldn't weigh in on this one 'cause I don't load on a MEC. My shuttles are ALL solid brass and really simple to load.
However. When I first started using APP is was a really light color, very dusty, and didn't run well thru my reloading presses. I don't know exactly when the formula changed, but the latest iteration of APP runs thru my Dillon 650(s) like grain thru a goose. The only change I made was the powder charge bar. Switched out the small bar for the large one. Very little dust now.
In all fairness, I do get an occasional "bridge" but infrequently enough that I don't care. Since I load full cases with no fillers, the occasional bridge is very obvious and simple to correct.
I really like APP. Oh, I also use it in my brass shotgun hulls.
Coffinmaker