Okay, maybe Gentium won’t work well as a weblog font after all. I couldn’t tell the difference when I made the change on my home Macintosh, but on my XP machine at work the font is much much too small.
Which adds insult to injury, because you can’t resize it. I now have a greater appreciation for Georgia’s design than I did before; it looked almost the same on both machines.
I will be rolling back the stylesheet change, but thinking now more seriously about making the fonts user-resizable.