Now that the clean-up is complete, and we're in this new thread.
The point of this discussion is that DirecTV has both Harmonic and Tandberg encoders.
Most of the technology (on the ground) was deployed prior to the launches of D10, D11, and D12.
There is now latest-and-greatest technology that provides for better use of the bandwidth. As an example, the Tandberg EN8190 encoders:
"Tandberg also introduced the EN8190 HD encoder, an MPEG-4 4:2:0 product aimed at direct-to-home (DTH) satellite applications as well as the IPTV market. Goldman says the EN8190 represents a 20-25% improvement in bit-rate efficiency over the company's previous MPEG-4 4:2:0 model, enough for a DTH operator to add one more HD channel per satellite transponder. Tandberg was demonstrating the EN8190 delivering six HD channels in 30 Mbps of bandwidth using its statistical multiplexing technology."
In order to utilize the new technology, it would require an investment, which it appears that DirecTV may be embarking on with the recent addition of TruTV HD and E! HD as a 6th HD channel on two transponders.