If you put my name, martynx8, into the UKP search box, you will read two reports that I submitted on November 16, 2012, in favour of using cock-rings.
They most definitely work for me and, since posting my last comments, I have invested in a larger size ring which also goes around the scrotum.
My regular WG now uses both rings, one in varying positions on my shaft and the other around my scrotum. She is utterly brilliant at adjusting them during OWO and knowing when to release and remove them for my orgasm.
I should add that I am almost 70 and only have OWO, so intercourse does not feature at all. However, I do not have erection difficulties and use cock-rings because, for me, they really enhance the pleasure of an already superb experience.
Best of luck if you decide to try one. I bought both of my cock-rings on-line from Lovehoney and they are the very simple ones with a plastic toggle; no clips or metal teeth and very easy to adjust. The original and smaller one is made of plastic and the larger one of stretchy rubber. Both fit very comfortably indeed.