re: Am I correct in understanding that the SEC-Network will only be on AT&T Uverse?

Uverse is awesome, in most areas. Odds are some of your neighbors have it, check with them and see how it works for them. I did the door to door thing for a while, and very, very rarely had any bad feedback from my customers. Every now and then there would be a block in a neighborhood where the service was shite, but AT&T damn near always got it straight pretty quick.