Ours generally work at full rez. Are you sure you're not pointed toward a thumbnail folder?

The issue is not resolution, but jpeg compression. Highly compressed jpegs show really ugly artifacts around the edges. Attached is a screen shot from Photoshop showing enlargements from two versions of the same image. The one on the left is a minimally compressed jpeg enlarge 300%. The one on the right is maximally compressed (making the file much smaller). It shows a lot of blockiness that is not in the left image.

It appears to me that TiVo Desktop Server is applying this sort of compression before delivering the images to the TiVo.

By the way, I often see the same sort of blockiness in HD broadcast, especially in sports. My source is an antenna, so I can't blame a cable company.

It does have to transcode, so it may be that in the process, too much quality is lost.

If you see this in HD broadcasts, those are generally antenna dropouts.

Have you found anyone in the technical side of TiVo who might be willing to put in a feature request for the server software?

No, we haven't.