They definitely added a little more of a dead-zone into the center of the FF. This is bad for G25/G27 owners because there's already a large dead-zone built into the software controlling the FF.
Simulation setting does NOT apply to G25/G27. So it changes nothing. All you G25/G27 owners, stop wasting time with that.
To me, a lower FF setting with 'power steering' setting turned OFF, is much more realistic than a higher FF level setting with 'power steering' on when driving a car that is supposed to have power steering.
The 'power steering' setting is just unrealistic and poorly executed in GT5. It comes on all of the sudden at certain times, not like any real car.
Here's something else to consider:
I have two G25s, I bought both when they came out in 2006 or 2007. They both feel different. So the feeling and power from one wheel to next, both the same type of wheel, can be VERY different.
One guy's level 5 FF setting might be similar to another guy's 7, or 4. I think a lot of the variability has to do with how the gears are lined up, how the gears are cut, the amount of lubrication used on gears, the winding of the motors, the strength of the magnets used in the motors and other variations in the manufacturing process. That is when both are new- old used wheels feel much different than new ones too obviously.
Another thing, suspension settup on a car can and should affect FF feel and strength. Do some experiments with spring weight, camber, toe, dampers, etc. It can totally transform FF, as it should in real life. Obviously tires make a difference too, but I don't see people mentioning their setup and tire choice when talking about FF differences. You can 'adjust' FF by adjusting suspension.. try it!