Hi, I have three anchors for my 46C, I find my 44lb Delta works great in soft ground and mud but will not set into hard sand / clay. My 35lb Danforth works great in hard sand, mud and weeds, but does not have the weight and holding strength in soft mud and as you say can be a b#$ch when in large rocks. My Third anchor is a 45lb Manson Supreme, I find it to be great (Best) in almost every situation but may slip in light sand. In Heavy rocky area I use a trip line to help release it. I generally use the Danforth because it is lighter and easier to handle, I also use a light trip line with a float on the Danfoth to help in retrieval when it gets wedged in. The Manson is great but I always worry about loosing it or having it stole because of it's high cost so tend only to use it if I know I will be on anchor for a extended period with risk of bad weather. one thing to note is that after market or copy anchors do not work as well as Brand name ones. If I only anchored in heavy rock I would use a manson with a trip line. Good luck, there is no perfect anchor..
Pete