I have a G Field Premium Zone #0 and #1. I have noticed that the #1 had a clickier sound to the face. Is it possible that the insert is loose or is the #1 just have a clickier sound?

They should have a similar insert but it is possible that slightly different head shapes will cause the insert to produce a very subtle difference in sound and feel. The #1 if I remember correctly has a slightly taller face and sharp heel and bumpers while the #0 is the all around balanced shape with rounded heel and rounded bumpers. #2 is longer heel to toe with flat bumpers.

I also found the sweetspot on the #1 to be slightly inside the sight line towards the heel.