In version 5, coming soon, we've implemented some smarter  logic for switching sectional maps.  In a nutshell, the system is now  aware of which area of a sectional chart has map vs. legend, and it will  make better default sectional map selections.  And you shouldn't find  yourself flying on legend data any more.
It's not a seamless chart, but this should improve things for those of you on the boarder areas.
-Walter
 
I found this thread and was wondering whatever happened to the idea of seamless sectionals... sure would be great!