When I first read about smoking chuckies it seemed like folks were trying to mimic brisket. Personally I think chuck roasts are best utilized creatively rather than trying to mimic brisket, with one exception. For chuckies, think pot roast in the smoker. I have about dozen smoked chuck roast recipes I have modified or created in my recipe file that were all born originally from pot roasts I've done in the oven or on the stovetop over the years.
For the smoker I like injecting them with creole or seasoned butter, then putting on a rub or seasonings that match the flavor I'm trying to achieve. Wrap at the first stall with a small amount of liquid that complements the spices or rub. By then the meat will have absorbed enough smoke to flavor the beef so you know it was smoked. You can even include onions, garlic, jalapenos, salsa, etc in the wrap. Then take the IT to 200F for slicing, 205 for pulling. Will definitely slice and taste better the second day after flavors have played all night together in the refrigerator.
The gelatin and fat you capture in the wrap can be used not only for au jus but for so much more in gravy, soups, and pan fried goodness.
Yesterday I used a chuckie to make faux burnt ends, an idea I got from goingcamping here in SMF on another thread. Definitely not the same as real brisket burnt ends but pretty dang satisfying! No injection, just cube, EVOO, season, smoke, drain, sauce, and smoke some more, no wrapping. 4 hours at 235, then 3 hours at 275-300F. I over seasoned them with rub yesterday but today I can't keep them out of my mouth! They've got that mildly burnt sauced flavor and barky texture I love with burnt ends. Had them for breakfast along with a slice of roast beef I smoked at the same time yesterday for the first 4 hours. My wife is out of town, won't get back until tonight. I made the mistake of telling her about them. I don't know how they are going to last until she gets home so she can try them.