I recently acquired a Cycle Dynamics Ti cassette and I'm wondering how long it may last compared to a steel-cog cassette. Should I use it on my daily driver wheels, or save it for special occasions? I can't believe how fantastically light it is ~

I fond this recently - it would have you believe that only a slight reduction of mileage on a campy full Ti versus partical Ti

http://www.totalbike.com/articles/Campy-Shimano3.html

but one would have to also know what sprockets did they concentrate their riding as the smaller cogs are obviously going to wear differently than larger cogs.

I'd suggest saving a pricy full Ti for special events.

I think you would want to have two sets of wheels. that way you just swap wheels.