Not sure why (since I'd heard so many people here having problems with them) but I decided to try a Slime tube last time my front tube got too worn out to repair. I have had nothing but excellent results with it. Noticed a bit of weight gain but not enough to cause me any concerns on the trails. No poke flats, no pinch flats in a variety of riding conditions. One thing I really like is that I only have to top off that tire with air about once for every three or four times I do the rear (no Slime tube) tire. The Slime seems to plug the presta and it takes a bit of 'ooomph' on the pump to pop the slime plug from the valve (which is probably why it holds air so well). Anyway, I've been happy with it so far.