I did that to my 2015 4038R last year.

The 4640 display worked, but screen setup wasn't awesome, so I got an extended display for it.  Also had to buy a yearly subscription for section control.

I am now changing the 4640 over to the gen 5+.  I am told that the larger screen will let me go back to one display.  It also comes with autotrack and section control, so the extra cost of the display will pay for itself in 3 years by not having to purchase that subscription.