I noticed that hum when I was editing the video. I've never heard it on my computer speakers, oddly. Only in that specific video while wearing my microphone.
0-build skills - I'm right there with you
As far as the NixiChron goes - Jeff seems to be selling them without tubes on his site but I don't know if he has any in stock.
Personal favorite? I know this is a cop-out but each clock has it's benefits. The Nocrotec clock has much larger digits and is easier to read from a distance. The CWC clock has an awesome enclosure unlike any other that I've seen.
So which is more important? The tube size or the enclosure?
As far as the life of the tube - replacing tubes in the V600 will be easier because they are socketed. I don't recall for sure but I believe that the CWC tubes are soldered in place. I'm not sure which has a longer life - let me see if I can find any datasheets comparing them.