We're on our second MES; it's the 39-inch model with glass in the door, remote control, temperature probe, external wood chip "drawer" for adding chips and top-back mounted controls. Our first model was the 30-inch "black box" with no bells and whistles, which I used for over two years. We purchased both from QVC, and love it (even as I type, I'm in the last few minutes of smoking tonight's protein).
In both models, I've done Boston butt, steaks, lots and lots of pork spareribs, prime rib, turkey and chicken. What I hated about the "black box" was the neccissity of opening the door to add wood chips, losing all temperature in the process. I didn't know anything about pellet smoking trays -- I just heated it, added wood chips, threw the food in and waited. At the time, I thought the end product was good -- until, with the new one, I can control temperature and add wood externally... the first rack of ribs done in the new smoker made ribs in the old one suddenly feel like they'd been cooked by one of the fast-food BBQ joints that dot the Atlanta suburbs. My first big experiment -- duck -- was like a quick bite of heaven.