I happen to own a WTB Phoenix SE. It is a really awesome riding experience and like build exactly for my needs. Construction good, sizing good, angles good ....and also steel is part of the equation. While the 'regular' steel Phoenix is already a pricey ride, there exist a ti derivative. I do not see how I could enjoy that ti version more. Maybe someone should lend me his, so I could try, but no-one in my neighbourhood happens to own one.

On the durability issue: Concerning ti I think it is slightly overrated. Often I hear sayings of that it will last a lifetime and so on. I have seen too much proove that is not always the case. For as far I know early 90s Merlins are good. Of newer offerings I am not really aware how well they are put together, but ti is no easy material to work with and once you start saving by doing things in a rush you can easily mesh it up.

My personal reasoning is that I can buy a 1st class frame in steel and I can buy a 1st class frame in ti. They are not the same, but they surpass my personal needs anyway. The steel will set you back half the money.