I had a RP 8 years ago, luckily with nerve sparing, and although my erections were never as strong as pre-op, things worked pretty well, albeit with the use of a ring in the last couple of years as erections started getting a little weaker.(I''m 74). After reading up on the Vertica device, I took the plunge and purchased one on their pre-order scheme, total price £1020.
After using it for a couple of months I have to say things are looking up, so to speak! Erections are stronger and I often wake in the night with an erection, which hasn't happened for a while. After sales service is great, someone is always on hand to answer questions or offer advice. Of course I don't know how it would work for someone with severe ED, but so far so good.