Msalib,
I don't think it has anything to do with photo resolution. Thinking this may only be a problem with large photo collections, I linked my ATV2 to an Aperture Album that only contains about 2100 images from a recent trip I took to Tanzania. The first time the screen saver came on it used about 20% of the photos, all from the first part of the trip. The last couple days (I've only had the ATV2 3 days), it again shows about 20% of the photos, but this time some are from a 2 day period in the middle of the trip and another portion are from a 1-2 day period near the end of the trip.
All photos were from the same Nikon 300 camera (thus, the same resolution), but it still only seems to cycle only a small percent of the photos. Also, it seems this problem is not caused only by large photo collections. I also have the original ATV and I loved the way it randomly selected from all the photos! I hate the way the ATV2 works!
I don't know how to send feedback for the ATV. Does anyone know how? I suggest we all let Apple know what we think!
Dave