The ones at our costco are always very nice. Good size and quality. I've certainly seen folks with bad luck with them like any brand, but I've never had an issue.
I cooked 24 slabs of these last weekend for two different parties and they were great. Prep time was minimal. Not much trimming required and the membranes are already pulled which is nice when you're cooking in bulk. These are always my top choice behind Compart Duroc ribs and come at a MUCH better price.
I cook them often. They are one of my favorites. I have done well in comps with them also. As stated, minimum trimming, check for membranes, usually pulled but I have found pieces here and there.
I like that they are already mostly trimmed, but it kinda messes up throwing the rib tips into the batch of Keri's Hog Apple Beans that I'm gonna take a whack at.
Frank, I can't say about the spares, but I always buy the Swifts baby loin backs at Costco and we love them. Very meaty and the membrane is already removed. I cook mine nekkid at 250-275*. They are great.