Thats cause you seem to like Prosumer products
The HD in ZHD stands for high desinty as the modulation system allows more channel in that spectrum.
I actially avoid compaines that market "HD" audio as its a gimmick to nab consumers who dont know any better. Saying that, said company hasnt actually mention the term high definition but think its easy to work out.
Im from the UK and run full Zaxcom cause I respect the inovation they come up with, Its not just the record function though, its the remote control elemet of the whole system. I cant seem my work flow being anything else.