This is in response to foggysail as well. And, twistedtree, it was I who purchased your 88# Manson Supreme several years ago.
We are just now completing a Great Loop along which we have anchored many nights and in many conditions. Only once could we not get a set and that was in the Georgian Bay where the bottom can sometimes be shallow mud over solid granite. No anchor will set in solid rock. But, here is a recent experience that may raise your eyebrows.
Just two days ago I ran us into a shoal because of 30 seconds of inattention. A 30 MPH wind had pushed the boat out of the channel and I was unable to recover quickly enough. It was low tide so I thought to wait for the tide to rise and float free. Unfortunately, every time I did float free the wind would drive me back against the shoal. It was an impossible situation.
So, to keep me in place while waiting for Towboat US, I dropped the anchor hoping it would keep me in place although I had no confidence it would set. To my surprise the anchor set almost immediately with about 25 feet of chain out, no more than a 2:1 scope. It held for 1.5 hours against a swift current and that 30 MPH wind. I have no explanation as to why the anchor set and held against all expectations anyone would have. So, I am a fan of the Manson Supreme. I'm not saying that a Mantus or a Rocna would not be a better performer. I am saying that the Manson has worked for me.