Harry was coming around to the idea of polyjuicing themselves, although he did find some merit in Theo’s technique. Never one to follow intricate details, Hermione had to convince them that even if they broke through the wards, how long would it take? What state would their prisoners be in if the enemy inside had had hours to come up with a failsafe. They may not even be there when the wards did fall. Hermione had no doubt now that Theo’s magical ability along with herself and Harry could cause some massive destruction if they so desired. It wasn't about using brute force - they needed to be cunning. 