fish finder / depth sounder questions

[djquick_silver]

We are looking at getting a fish finder / depth sounder for the new boat that we picked up. We are currently looking at either the Garmin Blue series or Humminbird Matrix series. Can anyone post any pros and cons or problems that they have had with either of these units? Also would you suggest using a seperate Depth only unit for general running around on the lake? This boat is a 16' Malibu 162 bowrider and is used for dual purpose. Thanks all and any info would be greatly appreciated.