i guess it depends on who welds them. mine broke at 20,000. had it welded and was holding strong at 130,000 when i sold the bike. had two locals guys do the same fix and held as well.
if you can pick up one on the cheap though,go for it...
The crack will get worse and the motor will start to stumble and stall. I wouldn't ride it if I didn't have to. After breaking two "y" pipes (it's really an "H"), I went with the Fullsac and have been extremely pleased. The heat reduction on the right side is reason enough, but having two distinct exhaust notes sounds pretty damn sweet!