I'm not getting you here - afaik the fs7 and f5 look exactly the same..
Unless you use a higher codec available on the f5 - sr444 raw or I guess the 480 codec instead of the 300 one.
I've not played with the 480 but it seems appealing as at 300 the 7 seems just to lack a bit.
The f3 "magic" is obvious- big pixels like the Alexa - it is worth noting that Arri only went 4K by making a bigger sensor.
You will only get any magic from the f3 with and external recorder.
Arri went 4K by gluing 2 x 10 yr old Alexa sensors together...(65 they did 3 )..making a slightly bigger than FF sensor.. in 16-9 the new Arri is still 3840.. No 17-9 mode .. and only their new lens will cover the whole thing.. at $98,000 body only I would guess Sony are popping the bubbly at the news .. an actual new 4K FF sensor with a camera around the same price as the Venice. really could have blown them away .. their nightmare didn't happen..