Never having used a swivel I am on the one hand tempted to try one out but on the other wonder what is their value ?
OTOH, I hear a lot of white noise in regard to swivels failing and the pins not being up to the job yet I see and/or hear of so very very few reported cases of actual failure that I do wonder if much of the muttering is nowt more than hoo ha.
In all my years of anchoring out (though not as many times as I might have liked) I've most certainly had anchors drag yet not once have I had a component fail, even with boats where the quality of the ground tackle was most certainly in question.
"Do you think God gets stoned? I think so... Look at the platypus." Robin Williams.