Yes, a grenade did blew up under my posterior last night. I was lowering myself to sit down on the floor after being hit when someone rolled it under me to clear the room. Anyway, no lasting effect is felt to my bottom after the initial impact.
I can only say good things about this product and will be purchasing several when it is released. Berkut has covered most of what I wanted to say about it.
One thing though, I had a bit of trouble getting my gloved fingers into the rings during the previous testing and I managed to separate one ring from the pin as I pulled it from a weird angle. I guess it is more of a suggestion if it is not addressed already is to have larger and stronger rings for the pin.