Actully, if you are already used to the tables structures the answer is yes, it would be really time saving aparently. But then you have the issue of fit your reporting needs to the existant data structure, and for me the things has been, defining my data structure according to my reporting needs.
In the other hand if you are not familiar eith the old data structure, i'll be a really PITA trying to figure it out. just my thought.

So I agree with the others , i would make new structures and migrate the old infor to the new tables
i will be faster