Yeah, a lot of guys have already weighed in but I want to tip the scales a little myself. Remember that the USDA food safety guideline is that poultry is to be cooked to an internal temp of 165°. ?As you found out at 170° meat is still moist, tender and delicious. I wouldn't take a chance at serving chicken cooked to 160° unless the carryover took it up to 165°.
I never marinate a beef roast. Never. Have never seen a recipe calling for marinating one. Applying a dry rub should be more than enough unless you also wanted to try injecting a marinating liquid into it. Now, last week I marinated a pork tenderloin roast which turned out superbly well but that was a cast iron skillet recipe. I haven't smoked a pork loin yet but have cooked quite a few in the kitchen oven. A pork loin would take very well to marinating as well as injections.
Something could be wrong with the MES and from the little I read of other posts looks like Dr. K and Bear got you covered with solutions. If it were me, I'd have exchanged the MES 40 for another one a week ago. I'll scroll down to see if you posted the results of the ChefAlarm calibration.
Hey, daRicksta! Yeah, I actually smoked with the second unit. The racks are great now, but the temperature was an issue. However, now that I've added the small deflector, it seems that the temperatures are good.
I brought in some of the pork and beef this morning, and everyone absolutely loved the pork. On the beef, we can't tell what I needed to do. Some people said I should have smoked it longer, to 190 degrees IT, but other said that with the beef being so lean, I probably should have taken it off sooner for more medium rare (which I think is what Bear suggested, too). Others said I should just get a brisket next time. :-)
I may have to smoke something else this next weekend, just for fun, and to test out the temperatures.
What amazed me, but something you all said - and turned out to be true - is that I didn't need to add water, and everything was so moist and tasty. My wife watches this cooking show, and the guy there is saying to dab on marinate on the turkey every hour, but I told her I'd rather not keep opening the door, and that it shouldn't really be necessary because the MES is so well insulated.