Yes, direct LOS since I was at an elevated point (reservoir).
I've seen a little over 12,000', but that was at the beach, standing in the higher sand, and a little out over the ocean. Very unobstructed and interference free environment.
300', in areas with lots of housing developments, over which you shouldn't be doing this anyway, I was dying at 3,000'. I'm thinking interference. Every house probably had wifi.
Remember, LOS is everything. Yesterday from my place to a nearby river about 1 mile away, I couldn't make it at 400'. The tangent of the angle to the bird would be 400/5280, which gives an angle of about 4 degrees. Very shallow. And the elevation is enen a little lower at the river. With my neighbors house and trees, I figured I wouldn't be LOS at that distance. Shame on me but I jacked my altitude up and 200' higher, I could get to the river and beyond. I had just come up to an altitude that gave me LOS.
I was also experimenting with antenna positioning. I was using the radar display for orientation (Although with my eagle eyes, I could slightly see it without glasses or contacts. LOL)
For some reason 5 degrees or so off directly poimting to the nird raised my signal (RC was the limiting factor), and changing the antenna orientation to bring the antennas more vertical got me from 2 bars back to 5. The plane formed by the antennas needs to be perpendicular to the craft.
So for max range LOS is everything, with LOS meaning it could be viewed (nothing in between), and your antennas must be spread apart with the flat party pointing out, and oriented so the flat sides are pointing at your bird, and vertically so they point upward at a 90 degree angle to the craft.
LOS is a huge factor, and what is obstructing your LOS is big too. I was only 2,500' away, and a drop of 50', from 200' to 150' turned my signals off like a switch. I'm thinking I dropped my LOS through a long concrete building. Especially with rebar. I executed its loss of signal return to home, and I control back in 30 seconds.
Sorry, ridiculously long winded, but unobstructed LOS, and correct antenna orientation (experimenting a little with it), and an interference free environment (unless severe the first two dominate at close range), can kick the range from 1,000' to 10,000'. That much if you get a nearby building out of the way.