Tried the Jim Shockey Gold in my Lyman Mustang today with bullets I know will shoot well. The groups I got were very similar to what I was getting with Pyrodex. The JSG burns clean (compared to BP or Pyrodex) and there was no "crud ring" or excessive fouling. I fired three shot strings without any cleaning between shots and experienced no problems in loading. I was using 100 grains GJG fffg behind 250 gr Barnes Expanders, and also several shots with Hornady 300 gr XTPs. The XTPs grouped about as well as the Barnes, so now I'll have to try some heavier Barnes bullets.
Cleanup at home wasn't quite as easy as the advertising says, but it was still easy. I took the breech plug out (easily - no sticking there) and dropped it in a cup of water while I swabbed the barrel with a couple wet patches. A few strokes through the barrel with a bronze brush, then a few more patches with Butch's BP Bore Shine and the patches were coming out clean. I then took the breech plug out of the cup, and to my amazement all the fouling on the face was already gone!
I dried it up and finished off the cleaning with a coat of Rem-Oil to the bore. If there's no indication of rust in a few days I'll be sold on this new substitute powder!