I’m curious about how much weight the axle plus nut would change from steel to titanium….
a quick search found this:
Titanium is highly valued in the metals industry for its high tensile strength, as well as its light weight, corrosion resistance, and ability to withstand extreme temperatures. It's as strong as steel but 45% lighter
That should get us in the ballpark…. For identical sized parts titanium would be 55% by weight to the steel.
I like simple comparisons, so just round that off at 50%.
saving grams wouldn’t be worth the cost. Saving pounds; it would be very slightly easier to justify if you could afford it.
titanium full exhaust is about the only area I would expect there to be a ‘real’ benefit.