I've never gotten a very good "feel" for the car through GTR2 or rFactor. It's well-known that the tire model is compromised, and doesn't take very well to oversteer. I once found a page that explored the programming and explained that it was because the tire simulation basically "fell apart" at large slip angles; unfortunately, I can't seem to find it now. Another factor is the predefined force feedback effects, which are less than ideal and no doubt influenced your experience with the G25. Another still is the lack of visual feedback, which could be attributed to the stiff suspensions of the racecars, but I've just never escaped that all-too-familiar "floating" feeling in any ISI game -- it's not that it feels like I'm "driving on ice," to borrow the popular complaint, but that the car kinda hovers around like a sliding brick. Finally, in the process of searching I found forum threads that discussed other issues, including a somewhat popular rFactor Porsche mod where the 911s had a front weight distribution of 60%.

As always, user-created content brings its own share of troubles, which is another reason the ISI games, particularly rFactor, are hard to trust.
That said, assuming what I've been reading in this thread is correct, it wouldn't surprise me if I had an opportunity to play the latest update of GT5

and left with the impression that it was better than GTR2 or rFactor, as you say. As someone who enjoys spending virtual track time drifting RWD roadcars around, I value that tire "feel" and beyond-the-limit behavior just as you do, and beyond the fact that they generally simulate racecars with unforgiving race-spec tires, the ISI games just can't offer what we're looking for, at least not without deep modifications.
As for the last game you played, iRacing, I haven't tried it, but from all I've heard of that project it's extremely surprising to now hear that GT5

has a better "feel." In any case, that list of PC sims curiously happens to be lacking the only PC sim I've played that has mastered exactly what you're looking for -- the feel of the car/tires to pavement -- and that is
Live for Speed. If you get another chance to play with
Dzidza, I highly recommend trying the demo, if neither of you have played it.
Forgive me, that last comment of mine was intended as "
if this was your point, please don't start." I suppose the "if" wasn't clear enough the way I worded it.
However, I must confess I'm still not sure of the relevance of your point. Let's recap -- Fujiwara-kun and s15specr said the new update made drifting difficult, pointing out that the car snaps around when you countersteer under full throttle. BRracing_ProtoX then replied that that's how it is in real life. I responded to BRracing_ProtoX, stating that in real life, a car isn't that likely to snap around under countersteer. You responded to me with an experience you had in a FWD car.
I'll grant you that we never brought up a drivetrain layout, but the topic was drifting -- which commonly involves a RWD car -- and I was talking about cars that drift under throttle -- something FWD cars are certainly not known for. Can you see why your comment was out of place?