I still remember accidentally trashing a card in my Viper Circle Back stripper deck by creasing a corner during a failed shuffle. I wasn't a happy camper - E sold out and isn't restocking their custom card stripper decks, and they weren't cheap. (Seriously, if it wasn't so phenomenally expensive, I'd be tempted to buy my own cutter and corner rounder. I may still do so, since there's a demand for quality strippers beyond what's available at retail.)
I gave the deck to my fiancee's son to fool around with. Since getting a LO/t of shuffling practice, I trash cards once in a rare while now (bearing in mind I'm not a flourisher, since that tends to be harder on cards than most magic and solitaire games). But when either a crease or a tear appears, the card's done - save the deck for torn-n-restored, autographed card tricks, etc.
Unless you know your audience and will be performing under controlled conditions, use the cheapest decks you can perform with.