Very useful, not at all silly. ....how often you use it or whether it is worth it depends on what type of shooting you are doing.
A detachable cuff is very useful because you can leave the cuff alone on your arm for travelling around, and then clip the cuff to the sling for when in position...or you can use the sling without the cuff. I altered my my own cuff to be able to connect to a sling, but I'm sure you can buy them like the viking one.
But they do take practice to get into a stable tight position.
If you are not already familiar with better sling use, look up videos on highpower or national match shooting.
Tried to find a good picture of mine, this is a shitty pic but i'm not home to take a better pic.
It is an old Vickers
quick adjust sling modified with a cuff made with quick detach buckles and similar webbing.
in the pic the cuff is just on the ground.... attachment buckle to the sling is where the red tape is
Attached File