Although a really low-n-slow method is likely to produce and even better result, I managed to get mine tender, and the fat all melted within 2.5 hours.
Perhaps the 24+ hour marinade (mustard-molasses-vinegar paste, and a dry rub) reduced the cooking time needed to get a tender rib.
My Weber was probably between 250-300 during that time.
Also, when I start, I place my ribs directly over the coals for about 2 minutes on the meat side and 3 on the back. This gets a jump start on bringing the ribs up to temp.
Given what I had read, I had expected them to take longer, but after 2.5 they were pulling apart and I was afraid of drying them out.
They had a good smoke flavor (hickory chunks and Bourbon Barrel Oak chips), but it was subtle, due to the quick cook time. However, I think I would prefer a more subtle smoke flavor on beef ribs than what I prefer with pork.
I'll try a lower temp and shoot for a 4 hour cook time this weekend.