Even beyond any theoretical security measures one huge benefit of in person voting is it limits the available attack. With IPV to steal an election you have to find a way to either physically bring enough people to enough polling places to swing the election or corrupt the poll watcher system and steal it in the counting phase. With electronic voting anyone in the world has a chance to attack you. Anything that requires Joe/Jane Citizen to reliably or securely operate their computer is kind of doomed for a long time IMO.