This is all true.
The handling of the 4 gear better suits an aggressive style and is overall faster. I am the kind of drive who gets to a turn, handbrakes around it and blasts out to get to the next turn as fast as I can. the 4 gear allows me to do this, whereas with the 3 gear I needed to carry more speed and be smoother... with the B4 I struggled as it isn;t a forgiving car, but the X-6 is, and so can be driven faster.
the 3 gear doesn't give as much chassis kick, so this translates to a flatter car. What we found is on a slippy surface, standing start, the car just span its wheel without generating grip. Now the car squats and creates grip, far more than we expected it to do too.
but, with the 4 gear, the increased understeer caused by better drive and pitching of the chassis, is all but gone when on a typical UK outdoor track - such as Grass or Astro or mixture. The car is a real weapon here.
Plus, the mesh of the teeth in the gearbox is perfect
Chris