I am glad to hear your hip went so well. Maybe that is a good sign for your shoulder too, along with the new procedure. The guinea pig part sounds a little scary, but hopefully he has perfected the procedure enough so you don't have any problems. I don't know anyone that has had a shoulder replacement, but I know a couple of people that have had shoulder surgery. I don't recall what the problems were, but they are both fine now. I guess it is really pretty amazing what they can fix these days.
My fear is my ticker that is not what it used to be (heart attack) and my blood pressure is low. I got a couple of more stents a few years ago and lost my blood pressure twice which was scary. Felt like I was heading for the final window to cash in my chips. That is where my being a big chicken comes in. I do know some people that have had knee replacements and they have all been pleased with the outcome. In fact a neighbor in our cul-de-sac had his knee replaced a couple years ago by the same doctor I go to and he was very pleased with his outcome. Said his back even stopped hurting after he got a bit further along in his recovery and was able to stand and walk normally again.
Anyway, enough on me and back to the shoulder surgery that I hope goes well for you and the new procedure really is better and allows a faster recovery so you can enjoy your trains sooner. And also the best of luck with everything.