I'm using the DFGT with RBR
and have found the you need to have the "linear steering" option turned on. thsi option makes the steering much more realistic.
Also have the "multi-turn range" (i forget what it's actually called) turned on
and adjust the range scale to about 60%
this allows about 540' of total steering that is used by the game.
it allows you to drive without having to take your hands from the wheel (just like a real rally/ racing car does) in the majority of cases. unless you need to spin around on the spot because you've backed the car off the road and into a ditch!
but just play with that setting until you get what feels right for you.
some people do like to be swinging the wheel through 900 degrees to control a slide.
but watch any in-car footage from a WRC driver, and they never need to take their hands from the wheel in normal racing
look at this vid of Colin McRae
http://www.youtube.com/watch?v=4LKAYtaD_t4&p=496AFCA7FB4FF65B&playnext=1&index=2
he doesn't actually use any more than 360' of steering lock
But i found that 360' was not quite enough as it made the steering a little "twitchy", the extra 180' (540' in total) lowers the sensitivity a little and allows you to make bigger steering inputs without un-settling the car (simply turning too fast in this game causes bad handling characteristics within the car, as it would in a real road or race-car)