hmm well i'm going to say how big do you think tahu is to Tf because i never remember them putting out a human to bionicle scale guide. based of the toys their both about the same size right?
look i'll put it this way MeGrimlockKing if you have both figures or at least a toa Mata mock up post a picture or ask some one who can because i own all three tahu's however i never bought a g1 prime so then i'll answer