Sorry Jez but I dont agree that a curved shank has a greater double hooking potential than any other.
All that ever needed doing to the old rig was remove the barb, and use a smaller hook size. Thus 99% of the problems created by playing the fish in a too ham fisted manner dissapear.
Of course that still leaves the healing problems, caused by the repeat captures in too short a time period, and a good disinfectant will take care of a large chunk of them.
I dont believe that the fish nowadays are as naive re large beds of baits, and so are not likely to be recaught on whatever rig you use. That takes care of the rest of the problems.
But ok if you want to ban any rig bait or method on waters you control, go ahead. But I have used the curved blowback rig for years, without any double hooking ever occuring.