I purchased a MES 40 just before Thanksgiving. I've cooked chicken and BB's for a start. Didn't turn out like I hoped.
I next tried a pork sholder (4.5 lbs) which smoked for 11 Hours! I tried another one a week later which was about the same size and it smoked for 12 hours!
The problem I had was the temperature. I pulled out 8 different thermometers to find out none read the same reading. I finally used my digital probe and one that I pulled off my New Braunfel's smoker and they were within a few degrees of each other.
What I found was that the MES unit is off by 25° (lower) compared to the digital temp probe. Also, the meat probe inside the MES is 10° off (lower) than the digital. That wasn't something I was happy about. Because the unit tops out at 275°, with the 25° cooler difference, I am unable to crank it up as high as the unit should go.
I also learned that I have to preheat the unit for nearly one hour ahead of putting the meat on to let the unit heat up. I had to crank it all the way up to 275° for that time. If you set it lower the unit will keep turning off and it takes forever to get the heat ready to put the meat on. I should mention I use the water tray provided and I fill it with scalding hot water when I put it in the unit.
I think I have finally "Mastered" the MES as far as the heat control goes. Right now I have a 5.5lb brisket on with a fatty. They have been cooking at 225° for just over 3 hours. I am also using an AMPS with oak pellets.
Just make sure you get a good digital thermometer or two and forget about what the MES oven or probe says.
Hope that helps.