I think my erection lasts longer. I also feel that the slight constriction makes it thicker. Not sure if that makes any sense. But, I do see it beneficial.
If he contacts me I will tell him that starting with some silicone ones to get an idea on the sizing is a good idea cuz that's how I did it but now I only wear those when I have more in the steel one so long that I have become tender and I need something to give me a little bit of relief from the solid tension of Steel