I've now rewatched the comeback and noted when Atlanta snapped the ball with a running clock. They snapped the ball with 13, 9, 14, 19, 13, and 4 seconds left on the play clock. If they burn down the clock and snap the ball with no more than 5 seconds left on the clock, they take :41 seconds off the clock. If the Falcons snap with no more than 2 seconds on the clock, they take an entire minute off the clock. James White scored the TD to pull within 2 at exactly 1 minute left.
Unsuccessfully challenging the Edelman catch also saves the Patriots some time, though it's hard to quantify. The red flag is thrown at 2:11 when the Pats were hustling to run a play to negate any challenge. The Pats then run one play before the 2 minute warning. I think it's safe to say the challenge saved the Pats from having to run a hurry up play, which would probably be just a short gain, as they were in "run anything to stop a challenge" mode.
Given that the Pats had two time outs and scored with a minute left, they should have been able to still score with time to spare. Then again, the Patriots calling two TOs would also have given the Falcons defense some much needed rest as well. Also standard recognition for the record that different situations would have caused different results.