Did 4 roasts this morning, two 10oz initial and two 8oz initial. Same set up and processed used in all 4 roasts, pre-heat to 300° put in drum, 1lb setting D for fast drum speed, 2x4 under the front, P5 on heat to about 310° as read on B then P4/P3 to coast/maintain 315° until 7min 30 sec when fan kicks in, back up P5 until heat loss is recovered and back to P4/P3 until first crack. Drop drum speed to slow, pull 2x4, crack door and if not already at P3, P3.
With the 10oz charges first crack was 10:30ish into the roast, I was able to stretch first crack for 1:50, no more cracks. With the 8oz charges first crack was 7:45ish into the roast and stretched it for about the same amount of time at 1:45.
What I noticed most was that with the smaller charge, it seemed like I could control the temp rises and drops much better, and if my math is right the ratio of time in first crack to time to get to first crack was much better with the smaller loads. I pulled all four roasts about a minute after the end of first crack.
One thing is for sure, I'm having a lot more fun with trying to hit the sweet spot using the manual method rather than letting the B do the work.