ExploderWizard
Hero
Afaik, they haven't with the Character Builder - yet.
I have not experienced loss of data with char builder but I do have a question: Does anyone know if there are plans to make the houserules sections actually DO something? There are options for creating custom house stuff but its all just hot air. I would like to create custom powers and actually have them useable instead of just flavor text.
The monster builder has been really good. Nothing has vanished yet. I will make sure to export before updating though.