My dear Guppy
What didnt you understand about "economical" your suggestion requires 2 complete, approved separate systems, and that would be fun in a Citation cockpit. The cost of doing business globaly for you maybe should not be compared with a chap operating a C550. If you bother to read the original post then you might be able to make some relevant comments. There is an avionic upgrade also that would incorporate a dual EFB system ensuite, trouble is, it would cost more that the value of the aircraft. As I said earlier, There are a lot of opinions on this subject but this works for me and its inexpensive.