I use Slime as a quick repair on spoked wheel tire punctures, but find that it does funny things to the tire's balance during acceleration and deceleration. In addition, it can cause valve stem issues. I've not used the product you mention, but anything that increases unsprung weight is bad in my paradigm. My strategy for avoiding the common rear tire flat is to use a mud flap on my front fender. Your front wheel agitates pointy things as you roll over them. It is just a matter of time before something hits that rear tire and sticks. The mud flap keeps those pointy things laying close to the pavement or completely knocked aside, reducing your chance of puncture. It is a technique sworn by among London Moto-messengers...