Hello Greg--flattening is forcing areas with transparency to fully rasterize.

And I suppose the text has a drop shadow or other effect? Try exporting the PDF as Adobe Reader 4 (PDF 1.3)

This should flatten the file. The text will not be live anymore if there is an effect applied to it, the underlying image, graphic, etc. If there is text that does not have effects, it should still be live text.

Take care, Mike