I use a Simucube and in my opinion the FFB in ACC is very good but friction at standstill is very very low. Adjusting friction in Simucube software doesn't give me the realistic feeling with still standing tyres than raceroom. Locked up tyres feel absolutely marvelous to me in Raceroom. Both ffbs are good but for me raceroom feels a bit more like the tyres are rubber. In ACC it feels more like either word or very hard and old rubber... imo you just feel "too much" in ACC, like it's flooded with canned effects (not saying this is the case). In rfactor2 in comparison it depends on the car. LMP cars are much stiffer than GT cars so you feel every bit of the road with them but with GT cars it feels softer and the suspension and tyres dampen more bumps.