It doesn't sound like the make of anchor had anything to do with their problems. I've used CQRs, Rocnas, Fortresses, Deltas, and Danforth anchors over the years. It usually depends on the bottom and anchoring technique. I feel the Rocna is a great anchor for sand, mud, and grass. I say this while being on the hook for 210+ nights a year.

These folks just don't sound like they know what they are doing...hardly the "anchor's fault".