BEFORE YOU INVEST IN READING THIS THREAD NOTE I DISCOVERED MY ORIGINAL HFN INSTALL WAS NOT WELL ATTACHED FOR ALL THREE FEET. FIXING THAT AT CUKI79's SUGGESTION HAS FIXED THIS PROBLEM
I finally put an HFN in my Rainsong CH-PA to match my CO-PA hoping to have one EQ and gain setting for both guitars. With regards to EQ it is a total failure. Otherwise both guitars sound fine after EQ.
Frequency: 100, 200, 400, 800, 1600, 3200, 6400 Hz
CH-PA: -1.5, -0.5, 0.0, 0.0, 0.0, -1.5, -4 dB
CO-PA: +8.0, +4.0, 0.0, 0.0, 0.0, -3.0, -7.0 dB
This is pretty far apart for two nearly identical guitars with the same body shape and strings. Acoustically both guitars sound the same to me and anyone for which I've done that demo. The cheaper guitar has fiberglass for the interior layers of the back and end pin areas. It might have some fiberglass in the bridge plate that the more expensive one does not (there appears to be a white layer you can see at the bridge pin holes for the CH). But for both guitars the top has identical looking CF inside and out.
The two guitars in question (CO-PA left, CH-PA right):
First two shots are of the CO-PA and the last shot is the CH-PA.
Other than cleaning the bridge plate area with a damp rag on the second install a few days prior, I can't think of anything I did different. I've inspected the pickup placement and it appears identical.
It is hard for me to recommend a pickup that has this much variation across installs. I've installed a couple of dozen K&Ks & JJBs and to first order they all sound fine and about the same (and I have installed K&K's in higher end all CF and lower end Rainsongs with the expected similar results). After EQ both these guitars sound excellent but I am shocked at how far apart the two EQ settings need to be.