I vote no on this, and would prefer the timer to stay as is! I play 30 second rounds as I want a quicker game.
Why not allow them to finish only turning in cards, deploying troops, and troop movement after time has expired. I know it's tough when you take someone over and the timer runs out. you should be able to finish, but not keep attacking. You could exploit this to turn a 30 second round into 1 or 2 minutes, etc.
Fair enough, sounds good.