So, after 1 day of using the new antenna/pre-amp, I'm very impressed. My expectations were quite low, but I'm surprised how effective the antenna and pre-amp are. My antenna is located in the loft of a bungalow, with concrete roof tiles and concrete gable-end walls. Main improvements:
1. Less breakup of trails, indicating more constant reception of aircraft.
2. More aircraft in list. In fact the CPU usage has increased from an average of 8% to around 13% now.
3. Greater range in the directions I had problems with. New polar chart, showing the standard antenna vs. the new antenna/pre-amp in RED.