I think it comes down to disposable income, someone like myself who makes under $20k a year would have a much harder time justifying a Ti frame than someone who makes $100k a year. If the cost of the frame will keep you from getting the components you want then I feel it is a bad idea, if you can still spec the Ti bike the way you want then I would say go for it, especially if you plan to ride the bike unloaded quite a bit as Ti is a fantastic material.