I was skimming the dipsy section of Keating & Porter's "Great Lakes Salmon and Trout Fishing" this morning. If I remember correctly, they mentioned mono dipsies for getting down 30 - 40 ft, braid for 30 - 80 and wire 60 to 140. They did make a point though that both braid and wire can be run shallow as well and the harmonics are different. The fish will choose what they like best from day to day.