Yeah, they do add a level of cushioning to your step that foam doesn't (foam compacts very quickly, the gel seems to last longer). Hey, they aren't that expensive, try one pair. My husband swears by the ones I bought for his bedroom slippers.
The foam ones never lasted very long for me and didn't seem to help that much, but the jells did and they certainly improved things. They aren't that expensive, might as well give em a try and see if it helps you out. Sometimes if there isn't enough room in the shoe after putting the jell in, I will take what is left of the original lining out and that usually does the trick for me.