I have a pair of Mirage M760's that I bought back in 1989. I'm still using them, and they still sound terrific. They've also held up amazing well; no deteriorzation/flaking, etc. at all on the drivers. I also have 4 M260's in the same condition; literally like new.
I've been thinking about replacing the 760's with something new, but so far I've held off as I'm still very pleased with them.I use them for HT and for music with a Mirage S12 sub.
If you can, pull the front covers and inspect the drivers, and of course listen.
These are old models, but if the one's you're looking at have held up like mine have, they should sound fine.
Jack