Interesting.
I normally use 60% strength 100/100/0/0 in TM control panel, in game +100% strength with 40% low force boost and Pure 360hz effects.
In my thinking I want to send 100% of the FFB signal the sim can generate to the wheel, then trim the feel with the TM control panel (actually I haven't changed the TM controls in many months now), the low force boost, and sometimes a tweak to the realfeel.ini MAXFORCE and SMOOTHING values depending on the car/track.
IMO the realfeel values are a bit low for T500RS (5-10% or so), but that is personal preference and perhaps a result of my FFB settings.