LocDown
I have both the Navionics Platinum and LakeMAster Chips for Texas/Oklahoma. I live next to Lake Eufaula in Oklahoma which varies in depth 10 ft. throughout the year.
I have been running the LakeMaster chip for the last 4 months and like it better then the Navionics chip because it has features which allow us to offset the depth to go with the current conditions, highlight specified depth ranges and it cost less then Navionics chips. But you should check to make sure your lake is listed.
Currently Eufaula is only 2 feet low, but there are a lot of shallow areas that pop up after adjusting the depth offset. The Navionics chip covers a lot more states around us, so it still important to have if I should go to KS or MO.
George