I think hadeeth can be used to give us an accurate picture of the past IF they are mutawaatir or some aspect of different hadeeths is mutawaatir. If two mutawaatir hadeeths however conflict with each other or the Quran then they should not be taken as historically true.
The hadeeth can also act as a linguistic authority whether ahadi hadeeth or mutawaatir hadeeth. However THEY CANNOT INTERPET new meanings for the Arabic langague, like that hadeeth whose intent is to re-define the term Islam in a religious way using the angel Gabriel's supposed conversation with the last prophet Muhammad (sas).
However, hadeeth CANNOT be used as a source for our religion. As the Quran states that only IT is to be used for our guidance and religion.