Thanks so much for the reply! I look forward to my first cook this weekemdI cooked a 4 bone 6.25lb rib roast a couple weeks back with probably 2 inches of room at the top. As for turkeys, I believe my last one was about 14lbs. I spatchcocked it and it pretty much was spread out across the grate area. They both cooked very well. I would suggest looking into a secondary rack to use. I got the RT one, when I bought my 340 and it's pretty nice. I use it from time to time in the RT, but more so on my gasser for baking and casseroles.
It's a great little smoker, you are going to like it. It will hold on to the temp pretty much flatlined.