Started using them last year. Very handy if you use homemade leads and sometimes need to clip the bait down.
I usually fish rough ground and only occasionaly need to clip a bait down.
Breakaway Imps can be added to a 'Flapper rig' without cutting and tying.
Simply make four twists through the link to position the clip at the exact position to suit your snood length.
If you replace the hook the link is easily slid up to suit the shorter hooklength.
Not the designed way to use them but very handy and release every time.
No idea the difference between Imp 1& 2.