Hi Alex –
Without looking at your files, it sounds like the issue may be with thin lines and fine detail in the artwork. I’ve seen that time and again and many times, you dont’ have the ability to go into your vector files and increase the width of strokes, etc. You might try adding an adjustment layer to your comps with a slight gaussian blur. It usually will help hide the artifacts you’re describing.
Brian Collins
Birmingham, AL
http://www.atomicpix.com