Decided to stick with the 4000NEX as well (mainly because I can't return it anyway without a hefty restocking fee.) Some of the other factors:
Larger screen will be nice
HD radio
Ability to play HD radio or pandora, CD, etc. in the background while using CarPlay
Motorized display for reducing glare (I hear it is useful)
Removable screen for security
Still having some buyer's remorse though, so we'll see how things go.