This repair doesn't seem so bad. The problem with the repairs I have seen is that the builder screwed something up that I'm not going to be able to fix. Like the cracked head tube where the miters were clocked. Or the Waterford where they put the seat post slot too close to the seat stays. And they used silver, so it's a real pain to fix it right. There are tons of those bikes out there with cracks, just waiting for the owner to notice. So in that case, I would recommend someone else do it so I don't have to worry about it cracking again. If I had to do it, I would replace the seat stays entirely.