I decided to try their "45* and glue-it" technique last time I did crown. (*or whatever angle was half the corner)
It lasted two joints. On a ladder, with a nail gun in one hand, the crown in the other, now I have to put CA glue on one end, spray the accelerant onto the other end, hold perfectly in place and hope it doesn't slip right before the cure.....
With coping, the coped piece can just pivot into the corner, and sort of lock itself in place with the curves on the molding. With a good saw, some stop blocks (or this:
I actually used the CA and accelerant for the few outside corner joints. I previously would use hot glue, but the CA is thinner and doesn't squeeze out.