I placed some of the new Rhinodillos tire liners on my wife's bikes because she HATES flats and is willing to put up with a little more rotational weight to avoid them. The newly designed Rhinodillos have a tapered edge so they supposedly won't pierce a tube like the Mr. Tuffys been known to do from time to time (not really sure how frequently that occurs). I know Stuart has stated that he has proven to himself that they are well worthwhile when mountain biking anywhere near goat head thorns. Like any flat protection, I think it's a matter of risk vs. benefit assessment for each individual.