I now run 3 boxes in various configurations (to demo to customers). I have 1 with HDMI connected and NEVER get audio dropouts. I connect in Parallel a coax output and it drops out. Same box, same feeds to 2 different amps. That my friend has nothing to do with signal, it has something to do with the software.
And by the way. As I have pointed out many times. I have clear line of sight to Te Aroha. I get ZERO interference from the infill, I have dual feeds from my Aerial, one through an amplifier and one direct. All in top quality RG6 and all now using F connectors. So I can rule out signal, in fact I possible have too good a signal and am going to try some attenuators. I agree you can't rely on the signal indicator on the ET box as it also seems to have a bug in that I can get it to read higher signal strength by dropping my signal quality.
But as I said, the audio drop out is nothing to do with signal.It only does it on the Optical (Coax) output, not on AV or HDMI.
The above does not change the fact that the ET is a very good box with good support and great future potential. It just means it still has some minor issues to resolve (as does every HD DTT box that I have tried). The good thing is that as has been shown in the last few weeks there is great support right here in NZ that can quickly turn out new firmware to fix problems as they are identified.