Titanium does seem to give a little more than steel, and much more than aluminum, which is why they typically use larger tubes for the down tube (kind of like modern steel tandem tubes) it makes the bottom bracket more rigid and you feel less flex when you pedal. I've ridden a Ti bike that was built with a single size of tubing (it looked equvalent to OS tubing in diameter) and that bike felt a little "whippy" when you stood up to pedal. I think the more you weigh the more likely you are to feel the flex as well.
I like a bike made of titanium with a carbon fork for my longer rides, just because its so comfortable. I like the feel of steel almost as much, but find my hands and arms are more prone to tingling/going to sleep perhaps because of road vibrations. I've yet to put a carbon fork on any of my steel bikes so I'm not sure if that is the difference.

CMC