As to color I thought that the darker was tempered and the lighter was untempered. Someone earlier mentioned double tempered. What does that mean? Was it run through hot oil twice? Does that help? In my many adventures in flooring I have found that the darker the tempered flooring the better restistance to wear and tear. There is one brand available at some Lowe's or Menards in St Louis (each branch in town has a different lumber supplier so selection and brand of lumber varies by store) that has radiused corners. It is 3/16" thick and smooth both sides. I have used this indoors and out and had very good luck with paint adhesion and I don't recall this ever having an issue where tape ripped up the flooring. On the other side of the issue Eucaboard brand has been an issue several times when I have used it for flooring. I don't know if it is a different Tempering process or if the screen back somehow allows moisture in that the smooth back does not. I have had it tear when I removed the gaff tape I used to hold the sheets together. In my experience I would agree that you are suffering a material issue not a paint issue.