RE:BH vs. StageYou are correct, there are plenty of dissolvable frac plugs on the market. These plugs all require wireline to set the plug and subsequently perforate the casing before the interval can be pumped.
STAGE is different in that it acts almost the same as a typicall ball drop sleeve, except instead of dropping different sized balls to open sleeves, the entire sleeve is pumped down (with dissolvable ball in place). Its collet system latches into the matching profile in the casing and shifts open the port. No perforating or wireline required. Same size ball in every collet means nearly full ID after the balls dissolve.
Again, this all seems dandy so long as the collet doesnt get caught up on any debris, sand etc.... I dont know the dimensions of the system but I assume it is very near full ID of the casing which could become problematic. I guess time will tell.