So, I bought one just to see what it was like, I unpacked it last night but haven't had the chance to offer it up to a camera and lens combo yet. If I get a chance I'll do a comparison with my favorite Think Tank cover http://www.thinktankphoto.com/products/hydrophobia-70-200-rain-cover.aspx possibly not a very fair comparisson as the Think Tank retails for about ten times the price. But, when you have a potentially delicate piece of electronic and optical equipment that possibly costs more than your car on a paintball field in the rain that price tag seems all the less significant.
Think Tank and Aqua Tech are by far the best, I have used the Storm Jacket too, and while it does its job it isn't the most durable piece of kit out there, the proofing on the inside of the single layer breaks down far too easily for my liking.