Neal,
The horizontal orientation of the Garmin is good, but the vertical orientation of the EKP-IV provides a much nicer presentation for flying. Since we're flying what matters most is what's ahead of us, making the "track up" presentation the most logical and useful presentation, and of course GPS's with vertically-oriented displays seem to have an advantage in this respect. Both the EKP-IV and Lowrance units offer this orientation. Of course if you can't fit this into your panel then it's a bit of a moot point.
As for the Lowrance, I very much like mine. The user interface is, to my way of thinking, miles ahead of the EKP-IV, and a good bit easier to use than the Garmins. Like the Garmin, if you learn one Lowrance product then they all work the same, making it easy to have a 2000c in the panel and either a 1000 or a 600c as a backup unit or as a secondary unit available to your "backseater".
One of the other Lowrance advantages is that the Lowrance box is WAAS-enabled right out of the box. The diagnostics page shows signal strength for the GPS satellites as well as for the WAAS signal. When in any of the other screens a little yellow asterisk shows up in the top right corner of the display when WAAS is being used. And WAAS makes quite a difference in position accuracy.
The Garmin units win the contest hands-down when it comes to battery consumption, so either the Lowrance or EKP-IV should be connected to ships power. The Lowrance has a built-in antenna that works quite well, and its external antenna (which is lightweight and suitable more for "indoors" installations than external fuselage mounting) does a good job of picking up satellites if the GPS is installed in the panel where its internal antenna is hidden from clear view of the sky.
I think there are several features of the Lowrance that make it not just value-packed but also a very useful tool. The MapCreate program that comes with the Lowrance allows you to make high-detail topographic maps and store them on the units SD card. As an example, I have a Jepp database plus topographic map coverage of about 75% of Canada on a 1GB SD card. The only limitation is that individual topo maps can't exceed 500MB in size, which is no big deal since you can store multiple files on one card. Having the topo maps loaded in addition to the aviation database and base mpas gives the pilot a huge amount of information, far more than one would find on a sectional, and the detail level is automatically set by zoom level so the display doesn't get cluttered.
Jepp updates with the Lowrance are straightforward. I can't remember how much they cost - it just gets billed to my credit card, but if memory serves they're very much in line with the figures quoted for the Garmin, above.
Oh, by the way, did I mention that all the Lowrance features come at a price tag below $700? I guess for some folks that's the biggest single feature. Why buy a used Garmin when you can get a new Lowrance for less money?
