I've been wearing them for almost a year, and I still get rubs at the top of my heels. I've dealt with the problem by layering mole foam inside the boots. I have to use two layers of the foam or else it becomes painful to walk. And even with the foam, I can't wear them all day. This isn't really a problem for me as I only wear them for a few hours at a time anyway.
The mole foam strategy works well, but I do have to replace the worn out foam every couple of months. I was content to keep using this plan until my trainer gave a pair of Equifit Gel Bands as her gift for our barn party's gift exchange.
The next few times that I wore them, I placed them at the very bottom of my heel so that I wasn't stretching them out or stepping on them. They were comfortable in that position, and my boots didn't rub, but I only wore my boots for an hour with little walking around. I don't know how effective they'll be with longer wear, say at a show.
The gel didn't both me at all, and once I was walking around and riding, I completely forgot the bands were even on my feet. When I took them off, the gel bands were pretty warm, but my ankles were cool. There was no residue from the mineral oil, and I didn't have any kind of a reaction.