Both I and a friend have now had titanium mast tangs from Colligo Marine fracture in nearly identical manners as part of individual dismasting incidents.
It is our belief, though not legally proven (yet) that the fracture of these tangs represent a defect in design or material which caused or were a significant component relating to the cause of the dismasting. Both sets of tangs were recommended by the manufacturer as being suitable for the application in which they were installed, and installed under the instruction and inspection of well regarded professional riggers.
I have more detail on my blog if you are curious as to the specifics, rather than just cut and paste here.
http://oddasea.com/archives/142-A-bi...asting....html
In my correspondence, the manufacturer has disclaimed all liability or responsibility and won't even refund the rigging purchase. I will post his email reply if you wish, and over on SSCA you can see his official response and the email he sent me, if you're an SSCA member:
http://www.ssca.org/forum/viewtopic.php?f=4&t=16557
So, if you're considering or have already installed titanium mast tangs, especially from Colligo Marine, beware. Two boats have already lost their rigs where this part was the only noted significant failure subsequent to the dismasting. Pass it on to your friends.