Simon as I see it its not an either/or question. The kid is on the verge of becoming SOO quality, maybe higher. He always had the talent, and I recall seeing him playing full back in a rep game and played more like a 5/8 for much of the game...and was very good at it...thrashed the other side. Having Gutherson here was not going to be not having Tom T or Walker. More likely not having Brown or Wright. He was already signed for a not substantial amount.
If he was with Manly today the variables are legion. He could be full back and Tom in the centre. He could be centre. He could be 5/8. He could be on the wing. He's that versatile. Imagine a back line like DCE, Lyon, Taufua, Walker, Tom T, Williame, Gutherson...or Gutherson centre, Tom T full back. That's a top line backline, as good as any in the comp. Like Tom I see Gutherson as future star quality.