Hi John,
I'm very pleased with the RadarBox. I've got 24 aircraft on the grid right now, but only 3 are tracking. Actually this is a fairly high percentage for the US, but things should get better as more aircraft adopt tracking.
I use the aerial that came with the box, sitting in a S facing window. I get about 100nm to the S at the higher FL's (but remember I'm at 4000' with an unobstructed horizon). To the N, through the rest of the house, I get about 25nm. I've looked at external aerials, but I can't find anyone to install one, and I'm not the age where I want to be crawling around on roofs myself.
Dave