Here is what I found on my 4wd rides (X-5, MiD/B44, FS2) :
Top layout is more nimble; bottom gives more steering, specially on low speed corners, to the point that you can suffer from grip rolls.
On sleek slippy tracks, bottom position can make the car understeer massively, as both front wheels are sliding.
So for me, top layout is the base setup, and I use the bottom layout if the car lacks steering and if the grip is high enough.
HTH