Quick impression. I am a RSS fan, their cars have always been great, and these are no different. 3D model wise these are the nicest versions of these cars in AC at the moment IMO. looks great in VR, looks great in screenshots. Just waiting for nice skins now.
Physics wise, there is a bit of curiosity here since I think they are following the 1998 ruleset. The cars have ABS and TCS. In 1999 both are banned so I guess depends on what year's grid you want to make it'll make a difference. The GT-One model looks to be the 1999 model though, with the slightly different front/rear fender vent layout and I think also the taillight arrangement, also the 1999 car has front splitter which this model has, but 1998 car does not.
I am also not sure how that applies to the 333SP since that car runs as a WSC/LMP car which I think do not allow ABS or TCS, so also curious there. Other than that the car drives good, maybe a bit too grippy but I was using S tires(also just driving around Long Beach, probably kinda weird for Le Mans cars).
Comparing to the most similar cars to these, the VRC Prototypes from early 2000s, those cars are harder to drive as they tend to struggle for traction more(no TC/ABSin those cars by VRC, which I think isn't true for the cars in period as the LMP900 cars should have TC I think), but they are believably faster than these cars by a small margin around Long Beach.
Fun mod, it'll be interesting to see what follows these....maybe they should release some in period GT2 cars too....