Moongel is one of the best inventions of the last decade. Instead of old-fashioned tape, moon gel makes your toms and snare sound like they're gated, Eq'ed and compressed at the source!
Sound engineers love this product as well, as the drums sounds great already! In the end, the sound in the room is the most important thing, and this makes everyone's job easier.
The pads are very easy to use and can be cut as well to fine-tune the wanted damping. If they're dirty, use some soap and they're as good as new.
For snares and rack toms, i use one piece per drum normally. Floor toms I put one pad on the inside of the drum on the resonant head, and one or two pieces on the batterhead. This way I can tune the drums very low, still have a bit of ring, but the sound stays focussed.
I love them!