There's a bunch of good stuff out there. I would say that if you are trying to save space then the combo might be the way to go. If you have the space and will be navigating big/dangerous water I would consider separate units. Why? If the unit dies you loose your GPS and Sonar. With separate units you'll at least have one or the other for navigation.

Hello,

I've got a lowrance 104 w/ gps and it's pretty good with the navionics chips. What I did for backup and general safety reasons, was to add a lowrance lcx-15 with a seperate gps antenna. I did'nt split the signal, instead I now have 100 percent backup. It's a good set-up for me.

GREG