[James Gleason]

I don’t have an answer, but I do have an observation. I regularly do this with two cameras: 1) Sony HDV, and 2) Panasonic HVX. The Sony (shooting in HDV) always gives me a lower quality shot than that of the Panasonic (which shoots in true HD at 1080 or 720).
The Sony is always shows more “grain” and more “noise.”
When you say “enlargement,” do you mean you’re pushing it more than 100%? That would make your image soft. A 1080i clip in an SD timeline at 100% would allow you to see only a small part of the clip so it looks like it was “zoomed” in. Are you pushing this further than this?