What a difference appropriate materials can make!
This year I've re-woven it using 240 denier tight-spun silk and the thread came through it without any problems. I also used a better red. The result is so much better!
The cards themselves took quite a beating just like they did last time. I think I'll try painting the edges of the cards with nail polish again next time I weave with this type of thread. Getting enough "real" cards, like wood or bone, for a project with 400+ warp ends would be pretty expensive. I also think that tensioning would be challenging with cards that much thicker since the warp threads on the outside would need to be significantly longer than the ones in the middle.