Nicky I have used them (mustard variety) they work well when there is a constant flow of current past them. I use them in the river or middens sand bar they work a treat they consistantly get the fish in the scisors of the jaw. If you want detailed knowledge of their use have a word Andy Rutherford. He uses them alot in rivers. I have used them as a pennel hooks on the open shore, and they work, but carnt say theres any real advantage to a standard pattern. Its difficult to get enough turns of the trace line around them so when used as a pennel hook that doubles as a bait stop slipping can be a issue. Thats my experience of them hope it helps,,,,in flowing current their great well hooked fish easy to get off without ripping the gills out. I should add I have used them mainly in the river for the generic codling and coaly/whiting we get on the tyne.
The chinu hooks look better for the shore Iwould like to give them a go but as yet not seen them in the local shops....Any info on theese welcome.