Those sound reasonable. I was worried about the level of gray. My files do appear greyer than theirs. I suppose he wasn't too far off, but it wasn't really the quality of the scanner, so much as the correct levels.

*edit*
Bingo. Gray area. I looked at the exposure levels in the scanner software. I ran two tests on an area of the scan, one with the "highlights" bar all the way to the right, which maxed out the gray levels, and one just below the peak of color. Both TIFFs were the same size, but when made into PDFs, the first one was 290KB, whereas the second was only 30. Thanks Peter.

*edit edit*
Sorry if I've been sounding impatient, but I'm grapling with the thought that I might have to re-scan 130 awkwardly-bound pages. That is if Irfanview can't make the necessary adjustments.