Maybe 4th time is a charm. Did BB ribs tonight. Removed the membrane using the "start in the middle" finger technique (who was it I learned that from? CWM maybe. Whoever, thanks! Worked like a charm!) then rubbed with yellow mustard, sprinkled liberally with Dizzy Dust. Cooked indirect at 270° dome for 5 hrs without even peaking. Opened the dome and they looked loverly! Brushed lightly with Bone Sucking Sauce (Hot) and closed up draft and daisy. Pulled them off 10 minutes later. They were pretty much perfect. Moist and succulent. Tender, but still took a bit of tooth to get the meat off the bone (that's what it's all about, no?).
Thanks to lots of folks for helping with this, most recently Ron B., whose advice to BeerBQ today guided me in my efforts.