This looks like a problem of using Type1 fonts in early Mac OS/X and later Mac OS/X
The characters 'greaterequal' and 'lessequal' were never part of the old Type1 font character set. The Mac System (the part of the QuickDraw text engine) would pull these characters into the font from the Symbol font, supplied as part of the system set. The first versions of Mac OS/X tried to recreate this but the latest version of Mac OS/X does not do this anymore.
You could try to see if the 'greaterequal' and 'lessequal' characters are part of the font by looking in the glyph window of Quark7. Some OpenType fonts will carry these characters, if they do not you should use the characters from the Symbol font.
Malcolm