I have a T300, it works great on RF2 you don't need anything more really. The G27 pedals are much much better you only need to buy an adapter for them o work with the T300.
I also recommend you get the F1 add on if you do single seaters, prototypes or GTs (not needed for ovals and FWD cars), makes inputs more precise and you have a little better FFB feel due to the wheel's lightness although the ergonomy is bad, the thumb rest should be way more upwards for me.
On iracing the FFB isn't great so a higher end wheel like Fanatec CSV2 may be justified, but I never tried myself that wheel on iRacing so I don't know if it's worth the difference in money. For RF2 i don't believe it is as you can feel everything with the T300.