Every laptop computer that I've owned his required significant repairs under their extended warranty - that feature has been much appreciated. In laboratory instruments, the extended warranty has not helped me personally - BUT I've often encountered out of life issues. Having a longer support period would be appreciated.
I'm pleased by the extended warranties - but also by an important corollary: the instruments will continue to be supported for an extended period of time. It is always frustrating when an instrument continues to work - but some trivial support item is no longer available.