I got to spend a little time in an RC_F today.
I've got to say, unlike the IS_F, the RC is actually enjoyable to drive.
The IS_F rides like crap, has zero traction at the rear wheels, didn't handle at that great... Always felt too heavy and lumbering in the turns.
The RC, on the other hand, rides pretty good. It has a much wider stance, the handling is light and agile... I didn't really have a chance to explore the torque vectoring rear differential, but similarly to the IS, there's still not enough traction in the rear, when accelerating from a stop or low speeds.
The only real thing that would make it much more fun to drive, would be a 6 or 7 speed MANUAL transmission, and a stage 2 or 3 clutch, instead of the 8 speed automatic.... But Toyota/Lexus move farther away from manual transmissions every year. Lexus has no manual transmissions for any current year vehicle....
Bottom line though... It's not too shabby. And heads and tails better than the IS_F!