I have tried the trailing hook method for approximately 6 months now. Originally I used to replace my hooks with three split rings in descending sizes (6, 5, 4) to space out a smaller hook the same distance as the larger hook that was being replaced and to keep the hook in the same orientation as the original.
The primary reason for me replacing the hooks, was the large size of the standard hooks on my favorite spoons. This is not an issue limited to one supplier, most suppliers of salmon spoons seam to use size 3/0 hooks on their spoons and I have witnessed first hand the damage they can cause to small and medium sized fish. I guess if you are always using the spoons for retention of large species of salmon this size of hook is OK, but I also like to fish big rivers for bulls (C&R) and steelhead and you need a decent sized and weight of spoon to fish bigger water, but the hooks were just too big for the intended target or potential caused bleeding.
I have now given up sacrificing my fingernails to the gods and have converted to the method Dan has developed. It my earlier trials I use 20 lbs Dacron and had a few breakages and I also struggled with the knot. Now I use 30 lbs and a triple surgeon for the knot and have not had a failure in 4 months.
I use Owner barbless No Escape Hooks in a No. 2 or 4, depending on my target and retention has been very good. In the past 2 outings I am over 90% of hooked fish. A month ago I was down to approximately 60% and could not figure out why, until I checked the point on my hook. Replacing the hooks with fresh, which is a piece of cake to do even on the river bank, solved all my problems immediately.
I have also noticed that more than 50% of my hook-sets are in the corner of the mouth, either inside to out or outside to in. I can't recall when I last hooked a fish in the tongue or upper mouth or had a bleeder, which has been very reassuring.
Some examples:
https://www.instagram.com/p/Bd9B0pGBC8W/https://www.instagram.com/p/BgK6PsMnA7B/In summary:
PRO's
Less harm to fish
Improved numbers of fish to hand
Easy to replace hooks at any time
I seem to lose less spoons (could be me, but just seems that way)
You can customize your spoons with funky colours...
CON's
Occasional hook wrap around the line if loop too long
Extra cost of hooks, Dacron and time to replace