I am not sure how many MySQL developers are using HeidiSQL for development but I am sure those who are using it will be fan of some of it’s features.!
I have been using HeidiSQL tool for my php/mySQL development for a while now. (more than a year and half..!). Before few months I have upgraded to newer version of HeidiSQL which is 4.1 RC1. It has got quite new and exciting features, looks and skins are improved.