I can't think of any reason they would say that other than 5.8 offers more channels and the antennae are smaller. But 1.3 is far better at penetration and range for the power. I run 400mW 1.3 transmitters and I've been 3+ miles out on my long-distance quad. I'm using the same transmitters on my ALTA and MōVI but of course I haven't been that far away. 1.3 harmonics can potentially cause issues on 2.4 control systems, but that's easily addressed with a $5 notch filter. Although at 400mW and some degree of separation I've never had an issue on my ALTA. On my long distance quad I'm running DragonLink UHF.