Here's my mare, 18yr or so, was a barrel racer, had a foal and then used for trails. Mainly a pasture puff here. She doesn't seem to like me too much, but that's ok, I like her enough to make up for that, lol.
Our now-deceased (R.I.P beautiful girl!) QH mare, Delriah had the longest back I've ever seen and probably will ever see on a horse. It looked better when she was fit, but not by much. Crazy thing though? She had done everything and been everywhere. Supposively made it to the reining and cutting world championships as a 3 and 5 year old, was a junior level mount for teaching reining, lesson horse, trail horse, lesson horse again...and in her last years, a therapy mount. And she didn't take a lame step or form a sway back once. She lived to be two months into her 50th year, and even then had severe artheritis in her hocks, not her back! Best mare we've ever owned. Makes me wonder just how much conformation really counts for...
We also had Pudding, who was severely sway backed. She was 29 when she passed earlier this year. We put her down due to bad artheritis in her hips and losing weight because she had nearly no teeth. We wanted her to die happy and healthy, not suffering. Even swaybacked though, she was a gem. She came from an amish trader who had gotten her from a cowboy so she'd never really known love until we got her. Didnt understand grooming, petting, or treats. She was just a horse. After she came to us though, even though she was already in her 20s, she came alive. She was a lesson horse to be doted upon for the rest of her life, and she never took a wrong step. We didnt find out for years that she had only about 10% vision in her right eye, she was that good!