I don't see any discernible difference between our rendering and Adobe's with ICEPdf 6.1.x. The captures in the support case are all jpeg images which I would not recommend for PDF output, PNG is are superior image type when dealing with low resolutions images and text clarity.
From their example code I would recommend capturing 'PNG' instead of 'jpg' for the images capture. If they having trouble still with clarity then they need to increase the DPI of the capture. When they capture a page at 1.0 scaling the image is going to be captured at 72 dpi on most systems. They should be considering capturesat 1.5 or even 2.0 scaling factor to insure there is enough pixels to work with.
I'd recommend they try enabling the -Dorg.icepdf.core.imageReference=smoothScaled as a start. Other imaging issue configuration options can be found here, http://www.icesoft.org/wiki/display/PDF/Imaging+Options .