A brief update on my adventure with antennas and such. I substituted the FA ProPlus stick for the Nooelec2+ dongle, with the same spider antenna, same location, and saw a dramatic improvement in # of aircraft and positions. I suppose this is to be expected as I have a 300ft cell tower staring me in the face to the east, so the filtering helped plenty. Oddly enough, putting a FA filter in line withe the Nooelec2+ dongle made things worse 
Next, I mounted the spider antenna up on my chimney, to make the reception horizon as unrestricted as I can with the trees and hills around me, FA ProStick Plus dongle. I think I am at the point of diminishing returns, happily - positions and aircraft consistently highest I have ever seen, and my range seems to very closely match my heywhatsthat prediction.
I’m pretty happy with being able to experiment with the no/low-cost antenna recommendations by many, especially the excellent write-ups and testing from @abcd567
I have gone from an average of ~200 planes/10K positions/day, to ~700 planes/90K positions/day and much further out since I started this fiddling.
Here’s a polar map after several days’ running with the new configuration.
and the theoretical plot from heywhatsthat.com (10000 and 30000ft elevations)
