Fix it, don't chuck it out.
A friend of the guest builder had a Planet X disintegrate out of warranty, new chain stays fitted. All good managing titanium practice. Both sides had cracked, they were cut out and replaced with Reynolds tubes. The hardest part is getting it all perfectly aligned - but the only part anyone looks at is weld quality which although getting better is cosmetically not to my satisfaction yet.
I know the fusion pass is good, I'm sure the argon purge is good, the heatsinks are good, I just can't quite get the pulse settings sorted out for a beautiful filler pass. Titanium frame 3 (not pictured yet) is getting there though. None of it's as bad as the welding that was done on one of my frames some years ago by *name with-held*.
I've had some cracking advice from a few frame builders who know their stuff though which has been a great help, thanks, you know who you are.