I have not, but as far as I remember you can't use 1.2Ghz for airborne use? (Vut I could be wrong).
But in theory it can give more range due to longer waveform so it has better penetration power.
But if you want long range fpv, better and cheaper to rather use 2.4ghz/5.8ghz gear with very high gain tracking antenna on the ground (Yagi style antennas are great) and then use UHF on your r/c transmitter. This way you can go a good few Km away.