Titanium is a swine to work with having done many repairs over the years.
It was used a lot on Lockheed 1011 Tristars as tear strips. These were designed to help prevent cracks from spreading between frames and were redux bonded in place. However over time the Redux disbonded meaning we would have to rivet the damn things in place. The material was only 0.016 in thickness and was like a razor blade. Drilling it was a pain and so we would use cobalt drill bits.
Titanium Hi Loks are a personal favourite of mine as are Titanium bolts / screws. I'm normally one of the go to guys for drilling these bloody things out when people snap them / butcher the heads etc. I have lost count of the hundreds i have removed over the years. Also having a working knowledge of being able to decipher the SRM of not only Boeing but Airbus when it comes to using alternative fasteners..
I have used Titanium plate for various skin repairs over the years along with Stainless Steel and both are a pain.
OK - handy to know that yr the 'go-to-guy' here.