He had heard that there's more twist in the Ti jackshafts.
Yep. But there is more to it.
To compare materials; assume 1000 ft/lbs torque applied to a 1.5 inch diameter shaft that is 2 feet long.
Carbon Steel: 2.4 degrees twist at end of shaft
Titanium: 4.5 degrees twist at end of shaft
However, titanium has several advantages. Weight, obviously (56% the weight of steel); corrosion (Ti doesn't corrode...and corrosion will pit the surface and create/start small cracks that lead to failure in steel); fatigue life (Ti can be stressed over and over, usually at higher forces, and spring back without failure).
So, yeah, Ti will move a bit more but it doesn't really age/wear-out and it will be more reliable over time because you won't get corrosion cause cracks that grow and shear. And sometimes having a bit more "give" in a material is a great thing...a driveshaft and the shock loading it sees is the perfect application IMO. And one last thought...because the Ti gives a bit more, it will be kinder and transmit less stress back into to everything attached to it like bearings, gears/cogs, chassis, etc. Nerd out.