No affect to 4WS I wouldnt think, as long as you've got sufficient clearance at the rear for the wheel to turn (whilst in 'sport) to both extremes without rubbing, and that includes suspension movement while doing so...
I personally don't believe in lowering vehicles that arent going to be used for a specific purpose, as the factory setup is typically optimal for 'average' conditions - and my cars get a fairly diverse run, including times where ground clearance is bloody useful
But thats just personal opinion not backed up by much evidence...