Second day testing at my usual smoke temp of 225*. This time for longer time to see if temps remain stable. The Memphis suggested test was for 1 hour at each of three temps 180, 350, 550. My results were good enough for 1 hr at each temp yesterday that I only did 180 and 350 tests.
One of the main complaints I had before, was that the temp also slowly climbed on low/slow getting hotter in the second and later hours. So I ran 225* for 3 hrs. Sure enough the start up was good with mild overshoot, and then settle down to 225*/225*, then in 2nd hour slowly and steadily climbed. I had my square D in center/center. My other two sensors one on each side. The side probes followed the center probe but were mostly about 20* lower on left and 16* lower on right. At the end of the 2nd hour the square D read 295* and the sides were at 260s. The controls read 236/225 at that time. In the 3rd hour I had a brief down run to 248 center sq D, and then up again to 301*. The control read 225/225 most of that time with a brief up and down to 231/225 (at same time it was 301). It was up/down from 260's to almost 300 for the rest of the hour.
Conclusion: Beale Street control does not react properly on long low/slow cooks. Fans are off too much of the time.I suspect the Algorithm is flawed, and perhaps ash build up in fire pot sends temps higher. Each control I've had was different in performance. The first had an older program and almost burned up the BS, the second was erratic at all temps, the third allowed temps to rise with time and did not correct them.
Beale Street bye bye. Life is too short. Thanks for all the input and understanding. I will not comment further.