I'm with Cyco on build design is most important
Up until now Ti was the top of the line as it allowed the best "custom" builds where you could choose the qualities of the bike and a good builder made it happen. You got durability and a frame which will last forever (and is repairable!)
Now you can get custom Carbon! I assume they will be able to offer the same customization. As to durability and repairability - don't think it's proven yet. Some lugged carbon frame allow for replacement of tubes, stays etc.
I have two Ti bikes and love them. Was getting a carbon but had issues getting it so had to compromise for now and got an alloy. A light carbon for climbing is next for me. (Kuota Kredo or Khan or a Orbea Orca probably)
I'll agree with that. I thought a lot about carbon, and this forum is a jewel for info esp. on carbon frames. The Giants, Kuota, Scotts I see are so seductive....
But I think Cyco and nz are right: design and build quality is critical.
Also, at least for me, carbon might be an option if I were looking for a specific-event bike, but for general everyday use I don't see the investment value, at least on my budget. I think with the good Ti builders, you have assurance on material quality, tubing selection, welds, warranty, durability, and most important some good experience, not just the builder but with the material itself. With carbon, there are "changes" every week it seems on lay-up theory, directionality, etc. For a team bike, great, but for me, everyday, I don't know....
In terms of Bruiser's specific questions, from what I've learned so far:
1) ti can be as stiff as carbon.
2) the vibration damping might be a bit better on an all-carbon frame (but I'm not sure on lugged designs, the lug design and bond will be critical there.
3) durability = ti
4) cost: I'm not sure yet, a good ti frame can run from +/- $1300 - $2000- $3300, so a very wide range....