We do development on Firefox, and we see very very few edge cases where those two browsers will behave differently. In the last 12 months I can only remember on

We do development on Firefox, and we see very very few edge cases where those two browsers will behave differently. In the last 12 months I can only remember one issue we had with javascript and form submit where we deactivated the submit button. If you have a lot of compatibility problems, you are probably using a lot of experimental features.