I have a masterbuilt MES 40 and it's great. I leave it in the garage with the door cracked while I sleep, and I don't smell it in the house. It's amazing for doing butts, and whatever else really, but the flavor doesn't compare to what I get when I cook on my Lang, but I would still recommend one. It's always nice to have a backup smoker, or something for when it's rainy outside.
My Lang is the 48 patio model, I was really lucky and found one on Craigslist about an hour away from me, and had a friend with a truck and trailer pick it up with me so delivery was no problem. It is very heavy, but rolls really well and it's built like a tank.