My experiences with titanium at work are that it is lighter than SS and depending on the Grade can be stronger. We use Grade 2 when we want something stronger than aluminum and resist corrosion. It falls between SS and ALUM in strength. Grade 5 or 6AL-4V is much stronger than SS. Grade 5 TI will yield at around 120,000 psi and break at 130,000 psi. SS will yield at 30,000-45,000 psi and break around 70,000 psi. This means SS will bend before it breaks where as TI has little room from its yield and it's ultimate. We have a pressure housing that we are taking to 8000 meters made from this grade. It is more expensive to buy Ti than SS but marginally and now that the SS prices have skyrocketed, it may be closer still. The problem we have incurred is that many machinists are not familiar with it, the books say you are to machine at slow speeds with lots of liquid so the time in which it takes to machine something is now more man hours, and you ruin milling bits in doing so. As a company we have not welded the stuff because we do not know if any of our welding companies know how to, are certified to, or what damage heat from welding does to the material strength. For example 6061-T6 aluminum will turn to 6061-T0 in the heat affected zones due to welding significantly reducing the strength in these areas.
Jason