Apologies for the thread necromancy, but I wanted to record my views on it.
I've just tried one in a Rocket HD. It didn't feel too bad; a bit dull but that's what I expected, but, unfortunately, it was what I called a "stealth blade" - in other words, it didn't feel too bad, but it was doing damage. It opened-up a weeper on my jawline, which is one of the usual places I'm prone to getting them. In addition, my usual 3 passes failed to get particularly close. I did consider hand-stropping it, but, as I only had one of them, and I wasn't too bothered about trying to make it work for me, I dumped it. To me, the equivalent Shark is no sharper, but seems a touch smoother.