Thank you Prodigy. That was the key to my happiness.

Here's the settings I've settled on for now...
[MMOS Global]
Steering Angle Rotation = adjust every car, check controller settings screen for correct value.
Steering Stop = Gain 20x, Max 100%
Force Settings = Overall Filter 24 / Min Force 0% / Max Force 100%
Effect Filters = Off / Off / Off
Desktop Effect = Off
User Effect = Off
[re: Overall Filter- Found this was the perfect balance for me of this vs in-game FFB Smoothing. Even with high MMOS filter (75%), still gives lots of road feel, but still cancels harsh vibration from rumble style kerbs]
[rFactor 2]
In a default Controller.JSON:
"Steering effects strength":-10000,
"Steering effects strength#":"-10000 to +10000, applies to all steering effects (torque, resistance, static spring, jolt, etc.)",
"Steering torque capability":20,
"Steering torque capability#":"The maximum torque capability of the wheel (in Nm, obviously)",
In-Game:
Steering Rate 100%
Speed Sensitivty 0%
Car-Specific FFB 0.50 - 0.75 [depends car to car, I prefer lighter feedback than most]
FFB Smoothing 3
FFB Minimum Torque 0.0%
EDIT: Just wanted to provide one further update. I haven't made any changes yet... but I've been advised that FFB Smoothing may introduce input lag (I honestly didn't notice if it has), and MMOS Damper effect may result in tougher time catching countersteering (due to slower wheel movement). But I'm extremely happy to have it working and feeling great to my standards.
EDIT: July 1, 2017 : Found a much better option for filtering out the harsh kerbs, but keeping more of the amazing rFactor 2 road feel. See updates above.