I had a coil fitted two years ago, at the age of 59 and 10yrs post menopause. I'd started HRT around 12mths previously and had an unexpected bleed, GP referred me and I had a trans vaginal scan which showed a very slightly thickened endometrium. The gynae suggested I have a Mirena coil fitted to ensure my body was getting enough progesterone. I was reluctant at first as I'd had a contraceptive coil in the 80s and had to have it removed after just a few months. The gynae assured me that coils have changed since then and that if it didn't, by any chance at all, suit me I could have it removed again.
I decided to give it a go and it was fitted at the same time as they did a hysteroscopy and endometrial biopsy. The whole procedure was a little uncomfortable but not painful, I was warned I might get stomach cramps for a few days after but I was very fortunate in that I had no discomfort at all. I did have some light spotting for 12 weeks after but since then I can't even tell its there. I'd have no hesitation in having it replaced after it's 5 year lifespan

I know lots of people have different experiences but we are all so different in how our bodies react to HRT that all you can do is read up lots, chat with your gynae and try to make the decision that is right for you.
Good luck!
Suzie
Edit to add - Bombsh3ll posted while I was typing...my comment about having it removed in no way responds to Bombs great point that you're reliant on someone else to remove it! It's a great point and one that I didn't even think about at the time! Deffo food for thought.