Knock on wood or stainless, but I have had very little problems with my slides. If you don't count replacing 3 air seals in 3 years. Prevost paid all three times and I am the 3rd owner. No Stainless coming loose yet.
I don't think you'll ever get anything in writing from Prevost or a convertor on a used Coach and I wouldn't have let that be deal breaker.
I enjoy the slides, but I have kids and dogs with me on many trips. I'm used to slides, having had two other coaches with slides.
My slides are Prevost slides.