As it becomes more likely that the use of handheld gadgets while driving will be banned, the Globe tossed out a thought worth debating--if drivers are still allowed to use headsets, will they drive better? Or is the mere act of talking the problem? Noah Bierman talked to an MIT engineer who said, "Conversations are the problem, not the phone." A Virginia Tech researcher added that the act of trying to dial was also distracting.......