We have had U-verse for over 18 months and love it. I do have one question. A friend of mine said that 23 dB is too much line noise. He is an IP tech so maybe he is correct. Set up is Coex to RG then Cat6e to 3 HD TVs. I have a wireless N router to all computers.
Should I run cat 6 from NID? Will there be any improvments? My theory is if it is not broken dont fix it.
23.0 dB is not the noise level, it's the noise margin. There's a big difference.
The noise margin is basically how much additional noise on the line can be tolerated before the signal is completely degraded and unuseable. In your case, your line can take an additional 23.0 dB of noise above the current noise level and still maintain some form of operation (might not be error-free, but the link will stay up).
U-Verse VDSL normally operates with noise margins in the 12.0 dB to 30.0 dB range. Thus, yours is very normal. No changes to your setup are necessary.