Ok, so, I spent some time moving the smoker temp probe all around my Bradley digital 4 rack electric smoker twice to check the heat pattern. Set smoker temp to 220* and preheated for about 40 minutes. I opened the vent a little more than 1/2 way, as I've done duing all of my smokes. Outdoor air temps dropped from around 46* when I started this experiment to around 40* by the time I finished the second experiment. Very light breeze from the rear of the smoker. Burned up a lot of bisquettes during these experiments trying to make it as realistic as I could while smoking bricks.
Started on the bottom rack and worked my way up taking 4 readings on each rack. Put a couple of bricks on the 3rd rack from the bottom because I didn't want to risk real food while opening the door every 20 to 25 minutes to move the probe. Allowed the temp to rise to the max heating limit and back down to the lower limit after each move of the temp probe.
I found about a 9* to 12* difference between the lowest rack(warmest) and the upper rack (coolest) and a 2* to 5* difference between the left side (warmer), the side on which the smoke generator is mounted, and the right side. The smoke generator itself creates some heat, and the smoker heat element is at the bottom of the cabinet, so my data seems to make sense. I expected a bigger difference between top and bottom. Also, I've read owners of other brands of verticles saying just the opposite, as far as temps top and bottom.
In a second experiment, with 2 bricks on each rack, I found that the more mass in the smoker and the more evenly distributed the mass is in the smoker, the more even the smoker temps and the less dramatic temp swings seem to be. Another good reason to smoke lots of food during every smoke, as if I needed another reason.
During a real smoke I also found, although I know it was a very subjective observation, that when I smoked nearly identical pieces of meat, one on the third from the bottom rack and one on the bottom rack, the one on the upper rack seemed to have a smokier taste. Not bitter, just smokier. My assumption would have been the bottom piece would have been smokier since it would be getting the hottest, freshest smoke but maybe the smoke concentrates near the top. It did take the top piece slightly longer to reach desired internal temp, but just a little over 20 minutes more for a 4+ pound pork loin.
Different outdoor temps and wind speeds might change the the temp swings a bit but I would guess the temp distribution within the smoker would be about the same. Just one person's observations. I hope this helps others.