I just smoked some spare ribs on the MES with a smoke tube only, no chips in the tray. It was a large 6lb rack, 9 hours at 230* and the ribs were at 270* when I served them. They were very juicy and tender but not FOTB but the bite pulled away from the bone leaving it clean. Maybe a few more degrees would have been perfect. I smoked them for 3 hours and then wrapped in pink paper for about 4 more hours checking temp hourly and then bbq sauce unwrapped for the last 2 hours. The smoke tube ran out after about 6 hours but I was just looking for heat by then.
There is still a learning curve and I'm not sold on the MES but it was a good meal.