Greetings,
I own a couple of the BCW comic bins and have positive and negative feedback. Positives, they are extremely sturdy, easy to put together and aesthetically appealing. I only have a couple so do not know how high they stack, but another positive, is they 'locked' together when you stack them. Negative, as they are so sturdy, when you fill them with slabs, damn they're heavy - so if you have a lot of slabs that you like looking through them, moving the comic bins may be an issue.
Overall, I like them, and as I do not own that many slabs, they are perfect for me.
Hope that helps.