After reading Jeff's "smoking ribs, Individually technique", I decided to try a bit of the same logic with a Boston Butt. I took the Butt and split it down the middle. [Due to the bone it was about 6 lbs/5 lbs] I layed the two halves in my smoker, set it at 225 [Mes 30] and smoked it 1.25 hours. Had a nice smokey look all over it. Note I was a bit concerned about over smoking or drying out, so limited it to 1.25 hours.
I took it off the smoker, the thick portions had an internal temp of 90 the thinnest sections were 120. I was pleased that it was not too hot to handle.
Then: I put rub on the internal sides of the Butt and tied it back together with butchers string. Then rubbed the outside and then back in the smoker. I chose not to inject. Smoked at 270 setting, 255 actual, for 8.5 hours until the internal reached 203. Actually I pulled it and foiled it at 175 IT. After that I let the smoke die out, but it was on for 8.5 hours total after tying it back together, so cutting it in half did not speed cooking, thus, the butcher's string produced the equivalent of a whole Butt
I used the MES 30 wood pan for the initial smoke and my AMPS for the long smoke.
Was it good?-- YES. Probably the best I have ever done.
What would I do different. Salt the internal halves before the first smoke.  Smoke the 2 halves for 2 hours at 200 before tying back together. or Maybe use my AMPS for a colder smoke yet and set up at 180. I think this would keep the thinnest sections cooler until I got it back together again.
You can bet I will be trying this again. Hummmmm what would happen with a brisket if I split it???????