Hello Bonnie. Thank you so much for looking and commenting on my peekaboo card. It wasn't my idea. It was actually a CASE of a CASE of a CASE. We were playing a little game over at the Kit addicts group.
I'm glad you liked that card. About that metal tape: remember, I stuck it to cardstock, so it does quite well in the mail. I always cover my card fronts with a piece of cardstock (cheap stuff works), then the Post Office can't feel any small "lumps", and it helps preserve the card, I think. No complaints as yet.
So, the answer would be that it does as well as any cardstock that has been put through an EF. Hope that helps.