I find the idea of polluting my realfeel'ish FFB with artificial slipping-vibration outright offensive!! ...but I totally use it ...just a tiny little bit, like a fingertip on my shoulder "easy! smooth is fast. Pianist not lumberjack".
I use 40 for curbs and 50 for road. Zero smoothing (AC has some weird damping already, really doesn't need it, unlike rF2 for example).
Minimum Force I have on... 5? Really, only 5? Seems low for my puny TX wheel. I think Reiza recommended 20 or so (I have it on 12-14 in AMS, 8-10 in rF2 iirc). This setting used to sound like bullshit to me, but it really helps to feel sudden changes better if there is a constant force, also probably more realistic to have a stiffer center feel.
Haha, many people are adamant about using kerb/road/slip. I drive like shit without some slip, so damn those people.
Too high min force will make you miss some (important) nuances, I think. Then there's the question of adjusting settings to what "feels" most realistic, or to what makes you drive faster.
I'm too damn OCD about this stuff, to the point I adjust more than I drive.