Hi all
An old thread but thought I'd have my say.
Theoretically, as HDMI is a digital format, my understanding is that it is either going to work (because it's built properly) or it's not going to work (because it's flawed in its construction - or cut somewhere along the line). I also believe that length can be an issue. Can't quite recall whether the standard's max is 5 m or 10 m but basically really long runs may struggle.
Coax, on the other hand, not being digital can differ significantly depending on cable type, quality of the plugs and quite importantly, how the plugs are connected to the cable.
Cheers
M