I did a boneless rib roast on the mini-wsm last night.  It was a tiny roast at about 2.5 lbs.  Simple S&P and EVOO.  The single chunk of hickory I used was a bit much for my taste though, otherwise fine.   I ran the cooker at 275°F, and no diffuser.  Served with roasted tomatoes, zucchini, and baked potatoes.
My wife destroyed her portion by throwing it into the microwave for a couple of minutes....LOL...