I just came across some good info I thought I would pass on..
I called a very old radio repair place (I'll leave it anonomous) and talked to a person I know is "the" authority on 72.
I was concerned about the length and possible mistuning of my old Futaba 6XA antenna....but I'll leave that subject for now.
In the conversation, I discovered that the 72 link is a really good one...much better than I thought, and if there is no onboard interference (well ther'es the FPV). the range if you are high above horizon can be phenomenal. I learned that Nasa, way back in the 70's (could have been 80's) etc was given a couple of slots on 73 MHZ and they were controlling planes with on board telemetry at 60,000 feet AGL. and never had any problems. This, I am sure is an authoratative fact and they were only using Futaba radios...no mods except for frequency.
Soooo. I think that in view of this, unless I have onboard rf "clutter" interacting, I should easily get 4-5 mile range say at 45 degrees up from horizon... Meaning 4-5 miles straightline(not ground distance)...and probably much more...
Anyone care to comment on their findings on 72 range.?