Ok, so I ran my little test again, this time actually using the two different windhsield mounts - the original 2-cup vs the new mondo single cup mount.
I had noticed on my first day to work with the new single cup mount, that the Redline detected the off-axis adjacent K-band speed sign much later down the road. I'm posting a diagram here of my re-test I did this evening. The difference is about 300 feet in this particular scenario.
The yellow arrow at the top denotes location and direction of the K-band speed sign. Note there are some homes and farther back near the "old mount" detect area, a large 2 story brick church. The mounts were both placed in the same spot, just left of rear view mirror.
I make no conclusions why this occurs - just the facts...
Google street view: