Took it back to Road Course Indy. Changed T/C to 0. Is very similar it doesn't fall apart. The rear has slightly more desire to step out but it is highly controllable. Little more throttle on the corners and you might have your D1. I am not familiar with that side of racing but I think it might work well.
One notable difference was it felt more consistent entering and exiting corners, like someone said before about having to preemptively predict what the car was going to do. This is now a thing of the past. You are in full control of the cars posture. I used to wiggle around a little coming in and out of corners as I tried to shift the weight side to side to prevent over steering under throttle but now I'm doing a nice linear curve. I am using the D pad so steering wheel users experiences may differ.
I use x for the throttle so with no T/C launching is much slower.
I have a feeling it might be a tad quicker (on a flat track) but at the cost of requiring more skill to drive cleanly. With the T/C on you have more room for a margin of error, but you do kind of feel like your in combat with the T/C in the corners. With it off if you do lose it all the tires catch fire which is something to be aware of.
Personally I think I would stay with the T/C on but that's just me. With it off, it may well be your cup of tea. Then again I might see if I can get used to no T/C it does feel like its picked up some pace, tough decisions!