Hence I never posted my review on GTP (one of the reasons), but just linked to it. That way GT6 isn't a mandatory thing to review,
1. It doesn't kill the benefits, but it doesn't utilize them. The weight transfer effect, used as the only FFB effect in GT6 (apart from some curb and off-track rumble), is causing oscillation because the FFB is much much stronger than the G27 that the game expects. So because the G27 is made to be more tight around center to remove the FFB deadzone the CSW v2 oscillates a lot. Only way is to turn down FFB strength and fiddle with the settings until you are either comfortable with it, or that you are on G27 strength levels.
2. Smoothness - The limit is the G27 driver on the PS3, but its pretty smooth. Its basically the same as PC as the update rates are the same internally. The only hing that might differ is how fast the driver updates the wheel information (polling rate), but there is no difference. Both are at 500hz as far as I know.
Precision - The CSW v2 is as precise as on PC, as the read out internally doesn't change. The limit is again the G27 driver. So technically you can't be more precise than a G27 even though the CSW v2 is more precise.
FFB Strength - As said earlier the CSW v2 is far too strong and differs too much from the G27 for comfort in this department. This causes severe oscillation at default wheel settings and in-game strength at the default of 5. Again I only had the oscillation issue with Gran Turismo on PS3, so it is definitely a game issue and not so much a hardware one.
3. It is worth it as it allows an easy switch to GT7 at some future point. Is it worth it for GT6 alone... hard to say and I would tend to say 'no', because even though the quality of the FFB is better and the wheel is as friction free as a G27... you just don't even use 5% of its potential in GT6.