We're in this boat, too. We have one window with a blown seal that we have to replace . . . but several more that we want to replace to get rid of some bad drafts and improve some cold rooms. We've done a handful of replacements here and there (all vinyl). But going through the process again. We've been pretty happy with the vinyl in the ones we have done, but those were smaller windows. We have some much bigger ones we want to get done as long as we're going through the trouble.

Anyone here who was done vinyl on large windows have any issues with them failing/warping over many years?

We had the guys who did a few replacements come out and quote vinyl again. Then a competitor come out and quote fiberglass . . . the fiberglass was pretty outrageous. Basically 2x. I like the pros on the fiberglass, but holy crap . . . the cost was pretty crazy. Thinking it's probably better to stick ti vinyl and take my chances. No issues with the smaller ones we've done and it's been about 10 years.