I had my right hip replaced 3 years ago, at the age of 51. I'd worn it out with big mileage running, rowing, bone spurs, arthritis etc. I had been in pain for 3-5 years prior, with decreasing range of motion, bone impingement at the top of the pedal stroke, etc etc.... I put off having the operation for years, nervous about replacing something "natural" with a piece of metal/ceramic/plastic--- but when I finally did it, I was delighted with the results. I was cycling on an indoor trainer within a week, and on the road again within 2 months. My surgeon has said there are no real restrictions on activity with the anterior surgical approach--- far less worry about dislocation, etc. Yes a severe crash could break the implant-- but it would have to be a crash sufficient to fracture a natural hip as well.... so the risk is about the same if you're going out on the road, regardless.
I have regained much of my original hip function, and I am pain-free--- so I am a great believer at this point. I suppose I could run into problems 10-15 years down the road, but this new hip has allowed me to continue my athletic life, which is worth a million as far as I'm concerned.
Being fit and healthy before the surgery leads to better outcomes, of course--- which to my mind is even more reason to get the operation before pain and disability rob you of fitness!