This is a question of the "correctness" of the implementation of physics.
Who has it "correct"? RSS? FSR? The Racing Rats? Thegost? ACFSK?
We cannot know how "it's right", cause LMDh class is fresh, very little data is known about cars, except for basic parameters.
I often wonder about this. Why are people so willing to pay premium price for mods, when physics is so subjective and it's unlikely to be 100% correct?
The best case scenario, modern road cars have lots of documentation and driving impressions info but even then you can't know every variable. And different model years often have slight changes that manufacturers do that are not documented (unless you're the type to trawl the specific forum relating to that particular make and model).
Old road cars and new cars that were just announced a few weeks ago often have incomplete documentation. Build quality may vary because of lack of Q&A in the old days (e.g. you don't expect all 250 GTOs to be build to the same standard). New cars still go through testing phase and have lots of changes in driving dynamics, and sometimes concept performance targets are not met (or exaggerated claims).
Race cars are even worse because of the amount of stuff that are swappable and the constant development race. Like in F1, teams keep bringing new parts to every race. Even in the same weekend, cars can handle completely differently from quali to race just because the track temperature changes and affects the very sensitive Pirelli tyres. Even the biggest brains like Adrian Newey can't comprehend why sometimes they lose or gain performance so drastically. Don't mention porpoising which confused almost every team last year and doesn't come up in their wind tunnel/simulator predictions (which costs many times more than even the most sophisticated home simracing rig). LMDH, most of the cars are still new and specs are highly guarded. Manufacturers can claim x downforce levels but on race day it might be slower than expected. Let's not mention BOP as well which can change from race to race.
Old race cars like historic F1 cars have even less documentation available. You're basically just basing the performance off engineers and drivers recollections which are several decades old. Lots of these constructors don't even exist anymore, so the chances of finding actual blueprints are nil.
Then there are performance differences between teams. It's all well and good for RSS/VRC/ASR to release a 2023 F1 car, but which team? A Red Bull and Williams are going to have drastically different performance and driving feel. Even for spec series, sometimes there are little things the top teams do that makes it slightly faster than lower teams.
So when all is said and done, physics wise nothing is guaranteed. None of the mod makers and us players will ever get to drive the real thing back to back to compare and know for sure. Maybe the Simdream model is closer to reality, who knows? Or even a free mod someone just cooked up in their bedroom. Hell even ACC, with all the data from actual teams and driver input can still get things wrong.
Maybe it's just me, but personally I don't see the point in ever paying for a mod, no matter how good it is. A few months later I can find a free equivalent that looks just as good, and drives just as good subjectively (no such thing as objective here because of all the reasons above). Ironically the paid mods also have fake names and logos that you have to swap yourself too. If you make it paid then the least I expect is an official license, or something giving it credibility.
Sorry for the long post, but I'm not hating on anyone making paid mods. I've driven some of these cars (when it was still possible to find leaks back in the day) and they're genuinely amazing. But I've also driven lots of free stuff that are just as amazing, if not more so. And with the amount of stuff out there you don't really miss 1-2 cars that you can't get. In the long term, you have to wonder if these premium mods are making things better for the community? Will we see as much stuff being locked behind paywalls and patreons if not for these trailblazing premium modders? And for the modding companies too, their choice of what to make will have to be market driven now. That means "safe" choices like GT3/LMH/Formula cars when we could've gotten interesting quirky oddball cars or lesser known race series like DRM or Mille Miglia.
Just my 2 cents