Most preflight headaches arise from missing fonts.
Even though the font name may be very common, different manufacturers produce different fonts and if the fonts used are not exactly the same, there is a very strong chance that the text will re-wrap or otherwise change position. Use type 1 PostScript fonts. Fonts are not as reliable and GX fonts are not currently a standard. Each typeface typically has two sets of files, printer fonts and screen fonts. We need both to process a file.