Yay or Nay? Pros and Cons?

Do the boxes lose any integrity when broken down?

That depends. If the box is mint and taught, I would be less willing to break it down, but for boxes that aren't super mint, it would be the preferred route. I would much rather receive a box that was carefully flattened than folded, simply because it's less likely to get damaged IMO. If the game is CIB w/the styro, then keeping it boxed would be preferable since it will stay firm.

-Dain

I agree with Dain 100% on this one.
~~NGD

I usally request the seller flatten the box. Ive seen the us postal service at work to many time. When they collect the mail at transfer places the mail gets tossed on conveyer belts and some times the drop at the end is pretty far.

Not to mention we play basketball/football with sack of mail as well. Then if your box full of boxes are in the bottom of a mail cart and then heavy sacks of mail get thrown on top they could get crushed pretty easily. After working for USPS, I really don't see how any thing makes it anywhere.
~~NGD