I dont even use a ARC2 (i run SAFC) and this is a very informative explanation of how the adjustments are actually "tuning".You have to change how you think a little bit when you tune an ARC2. You aren't tuning low, mid, and high RPM ranges like an SAFC. The low knob increases the entire spectrum numerically. That by nature effects the low load much more than high load. Pulling 20Hz from the idle makes a huge difference, pulling 20Hz from 3000Hz at higher load goes nearly unnoticed. The high knob adjusts the entire spectrum by percentage. That by nature effects the high load much more than low load. Pulling 10% from 3000Hz drops you to 2700,(very noticable) where 10% from 50 drops you to 45HZ. (not quite so noticable)
The mid knob controls the transition curve, and is typically a constant as it is what matches the linear output of a hotwire MAF to the not so linear output of a Karman Vortex sensor. It's almost always going to be -7 in that application regardless of tune or fuel used.