Some of the font sizes in the TMG windows are larger in v9 than in v8. I have compared all preference settings in v8 to v9 and they are the same. See screen captures below.
Note difference in font size on the custom tool bar on the detail view in the background. Note the larger font sizes in the labels and data in the right hand portion of the Preference screen as well as the larger font sizes on the buttons at the bottom. These larger fonts in some cases will required me to adjust my layouts. I find no preference settings that control these font sizes.