He swears by the stuff as he's been down twice in the last year - totaling 2 bikes - but walked away with bruises and nothing broken both times. I'd never heard of the stuff until recently.
I have a seven year old Motoport CanyonII jacket that is the most comfortable riding jacket I've ever owned. I switched to a BMW SavannaII jacket though because the armor in the old Motoports was pretty lame.
I still use my Motoport GP-2 Jacket that I bought direct from the factory in Carlsbad, CA about 12yrs ago. It's a kevlar fabric with armor, very comfortable, all seasons (with layering) and durable.