I use the same type of sling as you, Radsbow !
Here it is :
http://ceciletoxo.free.fr/drag.jpg
That sort of sling have the advantages of both the common types of sling and not the drawbacks : finger slings tend to make fingers and hand contract unwillingly ; wrist slings do not contract fingers but the bow may be uncomfortably hanging at the end of the shoot. With the hybrid sling, no problem at all, but it need to be adjusted to each archer.
I highly recommend the use of such slings either for advanced ot biginning archers !