I have used Emgo slip-ons before on a cb350 twin. They looked fine and lasted for years on two different bikes, and generally sounded better than a MAC. I see no reason for them not to still be in fine shape. They still looked as new when I sold the bike about 8 years ago. Those pipe size adapters they come with suck though, and require some quite creative re-engineering to not leak.
It is very uncommon for any headers to rust to the point of being non-functional. Look like crap? yes `Holes that cause non-functionality? no