I do not want to start a pissing match here..but here is my reason to use LDF.
In Air Navigation system installations, we use LMR400 to interconncect transmitter racks, monitor racks, power dividers ect....on the INSIDE of buildings. As soon as we cross over to outside applications, heliax is the cable of choice.
I know the guy isn't providing accurate info to aircraft, but for mechanical strength, ease of installing connectors, and smaller OD cable, durability, I'd rather use heliax. But thats just me. We just have more problems with LMR than LDF (Birds eating the cable, LMR seems "tastier" than heliax LOL)
For backup VHF and UHF systems, we use LMR400FR, but for all main VHF and UHF comm systems, we use LDF4-50A up the tower with LMR400 on the inside of the buildings between the radio and the heliax.
On a positive note for the LMR, we use on almost all our radar work cables, and LF/MF applications, and it seems to work out pretty good. I especially like LMR200, WAY WAY better than RG58 or RG223.
Both cables are great choices, and I know everyone on here loves LMR400, but everyone has their "preference" i guess. The only real "annyoance" i found with LMR is that the center pin on the "N" connectors is very thin metal, and breaks easily. But other than that, great stuff.