I personally don't see a problem with Big Licking as long as it or the training causes no pain or damage to the horse. I mean, it's not my cup of tea, I think it looks stupid, but to each his own. I don't see any direct repercussions to the shoes themselves unless there is some limit to the amount of nails that should be used. They don't weigh enough to really hurt the horses muscular system (that I can see).
IMO the video where they show the horse going from the pasture through shod and ready to go; while a nice video that shows everything proper, it didn't cover how he was trained to big lick, so it just basically shows stress/pain free shodding.
Bottom line, hurt the horse and I have issues. If you can train them to big lick without pain or torment, then by all means, have at it, have fun and be safe!
Just my opinion