I have an old Trek that cracked across the seatstay cap lettering on both sides. A local framebuilder repaired them; I believe by heating and lifting off the caps, then adding a lot of braze to the stay end and replacing the caps. The offending letter got filled in on the worst crack.
He also repaired the cracks in the tubes of an even older Raleigh Competition that apparently went straight from jigging and tack-brazing to paint. Didn't ask him the details of how he did the repairs. (He did say that the paint job was excellent; that the painter did a really good job of flowing the paint under the lugs and that the paint was probably holding the bike together!)
Broke a Peugeot UO-8 chainstay years ago behind the bridge. I was a boatbuilder at the time and had a local rigger weld it up.
I doubt the Peugeot repair would have lasted forever. I'll never know. The bike died a violent death two years later. I full expect the other repairs to outlive me.
Ben