I've never had any big issues with braking and turn in in AC, though next time I play it, I'll probably start noticing and then feel very disappointed.
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The only issues I've ever really had is that the cars feel a bit weightless, and the way the engine/clutch works is a bit annoying. There's an auto-handbrake or something, so if you try to slowly take off on just the clutch, you can see the car trying to take, but it won't move and just stalls. And when you are stalled, if you just put your foot down on the accelerator, the car starts moving. It moves very slowly, but it builds up revs as if it never stalled.
That's something I feel PCARS does very well. Infact, call me foolish, but when I was learning to drive in real life, I used PCARS for rev matching practice, and it helped a lot. PCARS as many have said before has a very early point of no return, so the moment you lose grip in any way, you're doomed. I think a lot of PCARS' complaints came from people not setting it up properly, which I'd say is partly SMS' fault for not giving good default wheel settings, and for the adjustment descriptions being vague (not all of them are described). I've had it for two years and it's still not quite right. In AC, it was plug in and play, and from that point on it was fine. It's interesting, because it seems to be the other way around for controllers, as SMS has done it better, and Kunos haven't. I have high hopes for PCARS 2 though, and I'll be keeping an eye on it. Just without a pre-order, that's all.
And Forza, I'm not a big drifter, but if you drift a car in Forza, and then transition into the next corner, the way the car changes direction is very awkward in Forza. The way you can slide race cars is odd too, it's when you break traction that the game shows that it's made for a wider audience. But you're right, at its roots it does have some realistic handling, and it's very well set-up for the controller. I can't comment on the wheel, as I can't afford to pay $1500 for decent compatible Thrustmaster kit. And yes, that's how much they cost here (G920 is reasonably priced comparatively, but not worth it as it's not enough of an upgrade from the G27). I'll stick with my trusty G27 on PC, even though reverse doesn't work anymore.