Firstly you need to use Real Feel, rF's default FF isn't physics based so there's no point in even trying it.
I used these Real Feel settings:
[General]
RealFeelIsOn=True
ConsoleEnabled=False
ConsoleRepeatDelay=0.100000
SpeechEnabled=True
KeyRepeatDelay=0.100000
SteerForceInputMax=11500.000000
MinSpeed=10.000000
LogEnabled=False
DefaultMaxForceAtSteeringRack=-4500.000000
DefaultSteeringDamper=11500.000000
DefaultSmoothingLevel=0
[Chevrolet]
MaxForceAtSteeringRack=6500.000000
SteeringDamper=11500.000000
FFBMixerRealFeelPercent=100.000000
SmoothingLevel=0
[Grand Touring 2000]
MaxForceAtSteeringRack=4600.000000
SteeringDamper=11500.000000
FFBMixerRealFeelPercent=100.000000
SmoothingLevel=0
Note that both these mods are very unusual in that they don't require the force at steering rack to be negative. Had I played around with the settings I'm sure I could get the 911 wheel to perform better I was just doing it as is as it's interesting to see the effect some really raw physics based feedback had on it.
The 911 wheel only pulled out of donuts in LFS, except for the odd time it pulled out of it, the one in the video is one of its better attempts. It wouldn't have it at all in the 911 and I had just about finishing blaming Real Feel, the track, the mod and the weather when my jaw dropped when my DFP just reliably pulled out of it.
I did a variety of tests starting in 2nd gear not on the rev limiter (LFS only) 2nd gear on the rev limiter, 3rd gear not on the rev limiter and 3rd gear on the rev limiter (rF only). In every test I held full throttle throughout. I tried varying steering inputs to find out exactly what it took, I suppose more accurate measurements could be taken in LFS at least by looking at the steering gauge.
I recorded 15gb of movies, which was a mistake because I didn't have time to watch them all and selected a few and deleted the rest. I formulated my opinions separately to the video.
The donut tests were far more consistent, the wheel was fantastic in LFS pulling out of every donut I through at it. In rF, however, it just wasn't having it. As expected the DFP refused to pull out of a donut at anything other than 300 degrees at which point it worked in rF perfectly as well. If you were just buying or testing this wheel for LFS it would win hands down, the oversteer tests in LFS were genuinely impressive, it can deal with a lot of lighter situations although I couldn't really bring myself to say it would be usable given the rFactor performance and the failure on big slides in LFS. It was, however, a massive improvement over both the DFP and G25 and the 911 wheels strongest point. I was suprised though at how well the DFP did at 300 compared to the 911 wheel and the G25 tests Niels did, that's not to knock the other two but it just amazed me how close they were.
TBH I'm not convinced the 3 angles are the best to test, there's little point in testing 900 if they're still struggling at 600. I will do another test when my new rF dongle arrives (which may reduce any lag related rF issues) and compare the wheels at the angles people are actually going to use them at (720, 540, 400) mainly in rF with the 911 as that seems to be the trickiest test subject and I'll try the effect on both wheels of different smoothing numbers and other settings. This time though I'll be much more disciplined in finding a speed gear the same piece of road and try and find a way of more consistent wheel movement if possible and most importantly I'll only do one take of everything so I don't end up with another mountain of videos to wade through
Doing the kind of FF test Neils described would be interesting but you could calculate that result much more accurately by looking at motor specifications, the gearing and the rotating mass. What this test does show is how the wheel deals with very small changes in direction and it identifies any lag, given the problems I've been having with lag, especially in rF that may not be helping the 911 wheel. I put the throttle bars on so I could double check that the throttle (and presumably steering) had not lagged.
On a side note I should add the 911 wheel's fan never came on so heat shouldn't be an issue.