"titanium will last a lifetime" – maybe it's the waranty terms ?

"lifetime warranty" that sort sort of thing?

We absolutely promise this thing will continue working until it stops working.

http://www.foska.com/pasta/pasta-di-bici.html

I've got a couple of carbon fishing rods, one of which is well over 20 years old, the other a bit less (17 ish?) and both are still fine.

Conversely, I have a couple of titanium fishing rods. Both of them are shite.

From this we can conclude that carbon trumps titanium.

Can't we?

WTF, does fishinig have to do with bike frame design?
Are the stresses then same? Are they as complex? Could I co fishing with my carbon frame? Would I catch fish?

As far as lasting goes: a good well designed, well made frame of any material will just as long as any other. However once things start to get lightweight that changes for all materials. Effectively they aren't designed to last they are designed to be as light as possible and just barley cope with a set of designed loads. Exceed thoose designed loads and the frame will break, no wmatter what its made of.

Thats why companies such as intense have frames labelled FRO and there are designed to last just one seasons racing. Look at other companies you will find that the lightest stuff as the least warranty length especially if you race, no matter what the frame etc is made of. Thats becuase its built to be light not last.

attack top tube with cheap hacksaw for 20 seconds. See which one is perfectly rideable after. I'd imagine, in a lifetime, some scrote will probably have such a go. I don't think there is such a thing as a frame-for-life, too many variables in life that you cannot predict. Piano could land on it.