The topic has drifted somewhat from the original post, but here comes my 2 cents, with apologies.
I fly with a 740 on the panel and an Android tablet on the yoke. The 740 is typically in enroute mode, with IFR chart and scads of informational guages showing. The Android has minimal gauges, vector map, and Nexrad displayed, and handles all the "what if" scenario's such as checking winds, ceilings, fuel prices ahead, etc. The Android is typically the master, setting up and filing the flight plan at home and then sharing with the 740 when the engine is fired up. If ATC vectors me to a different waypoint, it's easier to find on the 740. If I divert myself for fuel or bladder reasons, it's easier to select the new destination on the tablet. So I would personally benefit from a bi-directional setup, and I can see where a 2-pilot crew would also benefit.