I don't believe what that site says about the nutrient pack not being ruptured properly and the product leaking. I smack those suckers so hard it would knock someone out and I've never had one rupture.
That's the damned truth. First time I used a smack pack I was worried about just this kind of thing. Then I realized you could pretty much run it over with your car to break the nutrient pack without worry about the outside rupturing. Well, maybe not quite that, but taping it onto a heavy bag and going a few rounds with it up there shouldn't cause any problems. Nothing like a little exercise on brew day!