Was this tender when sliced vertically or did you slice it across the grain. I'll have to look at the whole shoulder--haven't ever seen it to my knowledge.
We used to make what we called Texas steak--took a shoulder roast, peppered it and beat it on both sides with a metal meat mallet. Then grilled. It was good--had had it that way a couple of places in Texas.
I highly recommend a sirloin tip for a cut of beef to smoke. Unless you do a boneless rib roast. The sirloin tip needs to be sliced across the grain thinly.
That is a really nice smoke ring. A little shorter time next time, as you said.
And no, KitchenElf, you can't do beef to that temp. It doesn't have enough fat and collagen to keep it moist like pork. You can braise it and pull it, as you undoubtedly know.
And when smoking a brisket I think it takes some smoking and then wrapping in foil and steaming to get it really tender.