I thought native 'on' let the tv do all the scaling.
In fact, I thought that unless your directv box was sending a 1080p program (pretty much PPV and VOD at this point) that the tv did some scaling to its native resolution anyhow, which for the most part either is 720p or 1080p unless you have an old tv.
This is true. When Native is off and set to 1080i, a 720p channel changed to 1080i by the box, then the tv turns around and changes it to 1080p, multiple moves. On Native, the tv would just take the 720p signal and move it to 1080p.
Thats what I thought. So for those of us (like me) with current 1080p sets, almost everything is going to be upscaled by the tv anyhow. I dont know what multiple upscales does to/for you, but what I've heard is that you want to limit the number of rescales.
The issue is an enigma within a conumdrum. In the end, it's in the eye of the beholder. Everyone looks at pictures differently on various grades of flat screen TVs. To the OP, just do what works best for you.