I have the 800 stock coil, 6" coil, have had the 15" coil and now the Coiltek 10 x 5. I think it will stay on it for a while. Most of my finds are not really that deep, I would say 4" - 6" range. Well within the range of the 10 x 5" coil.
It is so good around rocks, brush, small clumps of trees...