I borrowed one from a friend, to try it out.
It's very good at grabbing the rope from the start of the pitch -- so less need for trapping rope with your feet, or pulling it through by hand, or waiting until you're a few metres up before putting on the jammer. It self-feeds better than any other foot jammer I've used.
The "rope guide" hook seemed quite snaggy. It easily catches tacklesack cords and (thin) footloops. Walking back to the car with my SRT kit on, I nearly fell flat on my face when it grabbed my footloop!
Although nominally ambidextrous, using it on the left foot reverses the direction of the hook. That should make it less snaggy, but also less convenient to use.
I had hoped the webbing design would make it more stable on the ankle, but it didn't seem much different from any other foot jammer in that respect. It's also noticeably heavier / bulkier than the Pantin.
Overall: interesting design, self-feeds very well, but snaggy hook is awful so I won't use it.