Greetings Victoria..... These guys all have some excellent suggestions. Let me give you one no one has said.
You are the new owner of an MES40. Great smoker. Once you check the temperature calibration, best to do that during the seasoning cycle, you'll be good to go.
Instead of attempted a fast and furious smoke, go low and slow because you can. Put your meat (butts), in the smoker, use an AMPs (Pellet type auxiliary type smoke generator sold by one of the sites sponsors), and go about your business. They will take 20 to 24 hours with zero maintance required at a cooking temperature of 220 degrees.
My cooking secrets, easy K.I.S.S. (Keep it simple....) Just before it hits the smoker, salt, cayenne, Onion, Garlic, and a very light massage using light brown sugar. The sugar liquefies, the heat causes caramelization, gives it that nice candy coating like and M&M (you can't taste it much ), encapsulating the meat holding the moisture inside. That's it, the old ways still work.
Figure 1/2 to 1/4 lb per person, since we don't know if they are college jocks or classical ballerinas. Figure an approx. 35 to 37% lose in weight from rendering during smoking. Do not expect a red smoke ring on the meat, it's an electric so it ain't gonna happen.
You can cook these in advance. I highly recommend it! Cook 'em, shred 'em, Ziploc 'em. You can add a little finishing sauce to up the moisture but I doubt you'll need it. Its really more about adding some wonderful flavors to the meat. If you do it before the Ziploc, it gives it a chance to marry with the meat while resting. Then a large crock pot the day of serving, better than a chafing dish for retaining moisture and not burning the meat. If you are offering BBQ sauce serve it hot on the side.
Either make you own buns, or get a baker to make 'em, You want the buns slightly smaller than a small hamburger bun but not as small as a biscuit. It helps with lose due to fools loading a plate. They can always have more IMHO and get a new plate each time! Oh, I forgot, free gratis Oh my! LOL
Remember, smoking has been around forever so as long as you use common sense and don't over think it, its all about the patience, seriously! If you are cooking something for 20+ hours to get to 200 degrees IT, nothing can ruin it too fast. LOL
Great suggestions above, and good luck with your cook. Being a Pro I assume you'll take the maiden voyage before the butts so have fun with it.
I personally right now do the most of my smoking on a MES30, small, cheap, easy, idiotproof. As to an MES40 one of the guys here is all about MES40's, and even with all the great assistance above, I suggest you drop him a note when you have your battle plan and see if there might be something he'd recommend. "BearCarver", I think most here will agree.
Have fun and I hope the bug bites you, we are all here as addicts..... Nothing smells a good a good Pecan smoke IMHO. Enough practice and you'll not go back to Dreamland again!
