I bought a bag this weekend from Menards (and in the past) Nice big size and distibution of pieces. Lit easily. Smelled good. I had some issues with the Pitbarrel in using it (burned perfectly 1/2 of the basket and then died out???), but I don't think it was the Lump's fault. When cleaning out the ash, I did find a lump of clay and rock. I only bought one bag, I didn't know about the rebate when I got it. I might go back now and get a few more.
From what I could tell, it is exact same Royal Oak Lump as I've got from Wally World. I don't think there is any difference between this and the Red Bag. And fwiw, imho, I don't think it is any different from the "large size" stuff they bag for other companies. This is just based on the fact that if they are using front loaders and can't keep a rock out, then there is no way they have seperating machines to only get large peices in the other bags.