Guys,
My boat previously had Lowrance LMS334ci units with internal GPS antenna's. Like I have said, on another post, I could lose the GPS signal if a Seagull flew over me. Although that may be an exaggeration, I'm glad I upgraded to Lowrance HDS units, last summer. They also have internal antenna's, but whatever Lowrance has done to eliminated losing GPS signals, they did an excellent job. Not only do they not lose signals, they pick up satellites quicker.
The comment about accuracy is a little off, in my opinion. A good quality GPS should be within 10 feet, not 100 feet, with either an external or internal antenna.
I think an external antenna would be recommended in any application that the GPS display is not open to the sky. Say in large covered Charter Boats. A windshield on a Bass Boat doesn't seem to be an issue.
When it comes to Lowrance, you can network an external GPS antenna into a Lowrance Net network. You can network one antenna into a number of displays. There is one problem with this setup though. It's the fact that the GPS antenna gets its 12VDC power from the network. You can turn your displays off, but you antenna will still be drawing power from your network. Over a few weeks on not using your boat, it could draw down your battery to low levels. Lowrance's solution to this, is installing an on off switch on the network power cable.
With internal GPS antenna's, when you turn off the displays, all power is off. The network is still powered, but nothing is drawing power.
Have fun with you new GPS,
BATMAN