It's possible that everyone else except me knew about this site. But I was very excited when coworker showed it to me so I have to blog it anyway...
This is a list of firmware updates for many popular DivX players on site of biggest electronics shop in Slovenia. (the site is in Slovenian, so are the instructions, but firmware itself is international)
But it's not just official upgrades. Most/some of these are hacked. For example - firmware for my player is better than original. It improves exactly the feature that bugged me - subtitles were too small and too pale. This hack adds a setting to setup menu for subtitle size and changes the font which is way prettier than original.
If you wan't to go even further, I heard that Softpedia Board is a good place to start searching for firmware.
Take your change with custom firmware if the official is not what you want. You can always go back to official firmware if you change your mind.