An IC Tobirama would never use Edo anyway since he himself labelled it kinjutsu.
@Avinash, this is the definition of a reflex:
'an action that is performed without conscious thought as a response to a stimulus.'
In Naruto, the stimulus would be an attack launched by the enemy, e.g. V2 Ay attempting to blitz Minato and his reflexes allowed him to FTG away. It was only due to Minato's reflexes that he was able to react to the stimulus (V2 Ay). Now, if your reflexes aren't good enough then your body will not react to a stimulus that is too sudden, or too quick. Tobirama and Minato's reflexes are on par from what we've seen in the manga; Tobirama's reflexes allowed him to react to a stimulus that was very quick, and a stimulus that even Naruto didn't register. This stimulus was Juubito.
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Minato reacted to a stimulus that was just as quick, not V2 Ay since Juubito is far above V2 Ay in speed, but Obito's Kamui.
I really don't know how to lead on from this because it's a bit difficult defining what reflexes are in Naruto.