Just when you think you've got this down, a curve ball is thrown at ya. I've had continued success with plate ribs over the years. Yesterday I put on a 4 bone plate that looked gorgeous using the same process, 50/50 salt and pepper in the smoker on low for one hour then bumped to 275º for the long smoke. After 8 hours the pull back off the bones was significant and they probed tender. Let 'em sit for 15 min on the counter while getting the rest of the meal ready then turned to slicing. Ran into meat I would say was medium to medium well but definitely not pull apart. Very disappointed. While the flavor was good and certainly edible, they were not fall apart tender despite the probing. Maybe it was just the luck of the draw for this specific plate? I'd venture to guess they needed at least another hour , maybe more. After being fooled last night I've put a note in my recipe app to shoot for a minimum of 9 hours.