My wife has an AT PRO, I have a MXT PRO, some times she kicks my butt hunting, sometimes I kick hers, I am going to get AT PRO or AT GOLD, my question IS, IF I get AT GOLD, and the 9 x 12 or the 8.5 x 11 will it be any deeper or as deep as the AT PRO I here the bigger the coil the deeper it goes?. I like that the gold has threshold it has helped me with my mxt to find thoes deeper objects like my $5 dollar gold piece it was about 14 inches deep I heard just little waver in the threshold i could have missed it in silent . I am really impressed with AT PRO and I want one. By the way on her first hunt in our front yard she found found a cannon ball and a spencer casing, CAN YOU BELIEVE THAT! and she knows how to rub it in.