I got a 30" black MES around Father's day 2012. It was easy to use and I made some great briskets with it using the Big Bad Beef Rub (plus some rosemary) on AmazingRibs.com.
I got the 40" MES stainless with window on Black Friday at Academy for $199. (Yes, I got up and got there at 5 a.m. to get it for $199.) Couldn't resist getting it for the price because of the automatic temperature control feature. I was having issues with maintaining constant temperatures with the old MES 30" and the cooking probe on my ET72 went bad. Plus there were times I could use the bigger smoker.
I seasoned the 40" MES yesterday. Wished I would have found the post below before I seasoned it.
http://www.smokingmeatforums.com/a/how-to-season-or-cure-your-masterbuilt-electric-smoker
Observations:
1. Right now, I am making my first brisket on it. It is taking considerably longer than my old 30" MES. (1.5x to double the time)
2. I read about the temperature probe issues with the 40" MES. I am lucky as the internal meat probe of the MES 40" and the ET72 are reading either the same or within 1 degree of each other.
3. The 30" black MES would put out smoke for the duration I was smoking. I am finding that I need to refill the wood chips every 45 minutes or so with the 40" MES. In addition, I need to soak the wood for about 30 minutes prior to reloading (so it will last longer.) I see about adding the pellet smoker. Not sure about that yet.
4. Love the timer feature. However, wasn't prepared for the increased cooking time so the smoker went off before the brisket was done. Luckily, I caught it before it had been off too long.
5. With the electronic control on top, I will need to get a cover. Found this link on another post and it appears to be the best option.
6. Read about calling
Masterbuilt and getting a retro-fit to help with the smoking. Don't know if I need it as I have model 20070311.
Any info or feedback is appreciated.