Funny thing about titanium, it is stronger per weight than steel, but it is much more flexible and elastic.
Again, I'm not an engineer, but engineers have made turbine blades out of titanium for over 50 years. These engines fly across country thousands of times a year under tremendous temperatures and pressures. Tolerances are critical in this application, and the parts seem to hold up? I understand that these engines get routine maintenance, but I would venture a guess that one trip across country would produce more wear than the most dedicated shooter could produce in a lifetime.
My interest would be in a "modern" design in a top break frame, not a rehash of a 100 year old design.
I don't know if it is practical or not, but it would be a lot of fun!