I have a T3 with a B2 octo. It is crazy light which is also a benefit when traveling.Indeed it is the ideal metal for use in salt water. AFAIK the only drawbacks are the lack of oxygen compatibility and the price. Unless you're tech diving, you probably can't even buy pure o2 for scuba, so the former is a non issue for most people.
I'd be diving titanium if I didn't have tons of other scuba toys to put my money into.