Bob, how will you be using this?
It's a shame that no one is thinking about these gadgets as 'tools' and asking you how and where you plan to use the boat, nor where you plan to install it, nor who is to use it (and therefore how important the user interface might be to a diverse crew). Instead, as with many other things with which we burden our boats, we zero in on price, how many esoteric functions & other second-order issues.I'd encourage you to reread Jon's comments. Which chart format DO you find most helpful, since it's the chart you end up using? How long will you be using this unit and/or keeping the boat? Where will you be sailing, and therefore how unique will your chart needs be (Bahamas later? Nova Scotia, perhaps)? And just what kind of flight planning and navigation needs will you *need* (vs. the gee-whiz functions that may reside in the unit and clutter up its operation)? Are you shopping for these with your crew, who might have their own opinions of the user interface if they know they'll be expected to use it? Will you mount it inside, outside, or want both options to be possible over time, as your use of the boat might change?Perhaps these real-world issues aren't of much concern to you, altho' they would be to me.Jack