 Thanks for the replies
Maybe two hds chartplotters could share info through ethernet, but it's really a moot point for me - buying a single 10" combo cleaned out my fishing savings (and then some!).
I will say that I'm pretty impressed so far with what I see. Haven't had it in the water yet, so sonar has yet to be tested. I have had time to play around with the chartplotter, and it blows me away. I upped for the Insight maps and I'm glad I did. What I see on the screen appears better than any Navionics chip I used with my old unit. In fairness, however, my old unit was a simple 3600ci, and not high def.
I have not seen the Basemap version, but I will say that for me the Insight upgrade is well worth it. I have incredible detail on the major bodies I fish (Erie, Lake Michigan, LOTW, Fox Chain). My major gripe with Navionics cards is that I fish several regions and need at least 4 cards for where I like to go. The Insight add-on costs less than two Navionics cards. I need to get on the water to test accuracy and refresh rate. In the driveway, the refresh rate is very good when scrolling beyond the screen limits, especially considering the amount of data displayed on a 10" screen.
Once the Navionics software updates come out I'll post how it compares to Insight. | 
