I've got a T300 and apart from tweaking the wheel weight between a few cars, am happy with the FFB how i have it set-up.
That's not to say that I haven't done a lot of playing around, but I always end up coming back to pretty much the same set-up
Raw / Gain 80 / Volume 30 / Tone 25 / FX 20 (Main Spring doesn't affect driving)
The bit when it went side to side back in GT4 is thankfully a thing of the past.
However you will find PC2 gives you a lot of options, so head over to the PC2 sub-forum and ask away, plenty of people who will help out.
Few very quick pointers, road cars are harder to drive quickly on a track than race cars, hyper cars are on road tyres they will not stop or corner as quickly as race cars - so drive them in that manner, tyre temp is really important - if your not up to temp on race tyres you will not have anything like the grip you expect.
Oh and the first combo it sticks you in is a McLaren 720s at Long Beech, which will spin its rears in 4th, and you start with cold tyres. Brake from before the 500 yard boards and don't try turning with even close to full brakes applied. It's much more demanding than GTS, but also more rewarding in that regard as well.
Have fun :-)
BTW this is a year after launch video that may be of interest.