Never used the lake master, happy with navionics. One of the neat things you can do with your unit is record your sonar and upload it to insight Genesis then down load it back to your unit. They have a free, social mapping side and a private, for $99 a year side, which gives you bottom hardness and vegetation. From what I've read it sometimes shows errors in other mapping programs. You can register for free and view all social maps in an area, including Montana.
