Smoked fresh picnics

rt64,
you have found out what i did a year ago. while i use an sm150 the heat source is still from the bottom up. your times are near what i do every week commercially.
i truly think that what is occuring is this;
fat contains a lot of water
as that water is heated it is turned to steam
heat always rises
so in effect what is happening is in the inital phase you are smoke/steaming. as the cooking process goes on you are getting bark formation as the water evaporates. or like my stick burner buddy told me you just turned a stick burner up side down (his are reverse flows). don't know how accurate that is but it works and works well enough that i simply do not cook butts as the yield from a picnic is 3 to 4% greater.
one suggestion i might have is to drop your hit temp for take out down to the 190 area. this has worked well for me but then again each unit cooks differently (i have two sm150's and one always runs 5 degrees warmer).
i have ran this difference along to a few chefs at the culinary school i graduated from. the only thing that seems to be is it is the steam formation but no one can pin it down for sure.
one thing is positive though,with 4 thermos reading within 3 degrees of each other it sure aint a thermo error.
jack