I bought a pair of full seat Pipers about 3 months ago on clearance. I’ve only ridden in them 5-10 times so far, but they seem to be holding up fine. I’ve washed them and thrown them in the dryer too without any catastrophes. A loose string here and there, but I haven’t noticed any seams unravelling or tearing.
Unsure how frequently you’d be riding in them, but especially if you can find them on sale I’d say they’re worth it. Mine were only $30, so even if they only hold up for a year I guess I won’t be too disappointed.
As an aside, I did buy a pair of Kerrits Griptek II Fullseat breeches on sale ($80) shortly thereafter and I love them. Again, I haven’t put tons of rides on them yet, but quality wise they seem pretty good so far and they’re very flattering. The material is a stretch woven fabric, so it’s very thin but is still quite supportive. Really great for warm weather, but there was also enough stretch to let me put some wool tights on underneath when it snowed here last week. They are extremely grippy though. My first ride, I was half tempted to rub some dirt all over them to get rid of some of the grip, so if you’re used to riding in knee patch breeches you might not like them. They’ve been washed a few times, and they’re still very grippy, but I don’t feel quite so “stuck” in them anymore, or maybe I’ve just gotten used to it.