I tried the road-biased setups and was really impressed, but i felt the diff's were a little loose on a couple of cars.
In the RA, i'm using a 20/40 diff, and it has less sloppy power oversteer. With the roady setup, the car would spin the inside wheel in fourth gear turns and the car would throttle steer inwards in a big lazy arc. With it turned up to 20% for the power side, i was getting a lot more obediance from the tail.
Same can be said about the FZ50, which i was running at 20/50. I use a higher coast side for the mid/rear engined cars to help with the lift oversteer. It keeps the car more controlled when braking or entering a corner (or both).
One of the other factors i find with the lfs handling traits is down to driving style aswell. That corner entry oversteer is associated with weight shifts, for sure. You see people coming off the brakes from 100% just as they turn in, and whammo, backwardsville. If you are more gentle with the application of the controls (as you would be in reality), the whole thing feels much more dependable. The softer sprung setups definitely help in this regard!
At a recent trackday, a corolla driver spun into a lake from a 150kmh corner. He went through an understeer/lift oversteer phase before shifting down mid-corner (because he'd lost speed and the corolla has a 2rpm powerband), and the tail jumped around. He said it had never happened before, but this was his first day with a stiff set of cusco suspension in it. Nuff said about that.
Beyond these things though, there does seem to be an inherent problem with the transition from grip to slip, which is only a problem when you break traction (so everything is peachy until then).