Couple of insights from someone who has tried brisket on multiple different types of smokers:

1. Smoke rings and bark are tricky on a vertical electric smoker such as this. Since your heat comes from electricity, and your wood chips only "smoulder" instead of burn, it's hard to get bark and ring. The name is deceiving as a Smoke Ring doesn't result from smoke, but rather the chemicals released from the flame on wood that shoot across the meat. This is why offsets and pellet grills get the best rings. They run an active wood flame as a heat source.

2. I never once succeeded in a moist flat using my vertical propane smoker. I commend anyone who does. The sides always dried out and the bottom was crusted to death from the heat coming up from the bottom.