Well I ride the extinct Lemond Tete De Course, and to me the ti/carbon combination is fantastic. The frame is just as stiff as an aluminum Cannondale, 3 times more comfortable, and has a lively ride.

Titanium is well known for dealing with big hits - potholes, RR tracks, heaves, big cracks, etc.
Carbon is well known for reducing vibrations.
The right combo does both.

In the right R&D dept. and good manufacturer, full carbon can pretty much do it all. However, I think they still lack just a little bit of feel to me, of which I can't really describe. In full Ti, if you want super laterally stiff, a custom maker like Seven can give you that but there will be some trade-offs.
You live near MA, so why not plan a weekend up in Boston, schedule a tour of the Seven facility, and arrange to test ride their ti/carbon hybrids. You are also in Serotta country to try them out.

StanSeven mentioned the softness to the ride. My only comment on this is that the bike is far and away smoother on rough roads than anything else I've ridden. Some people may feel that its sucking momentum. However to me it still is a killer climber. Tom Danielson won the Mt. Washington hillclimb on my frame, and was on pace to break the record (that he holds) but the weather turned nasty up top. He still ended up with 3rd fastest time in race history. Clearly a ti/carbon hybrid bike can be a monster climbing machine.