This tool is excellent. As a programmer myself, I appreciate the work. You have just put yourself and other logo makers out of work.
This will be used by veterans and rookies alike. It is well thought out and intuitive. I agree with StLee's suggestion to copy and paste RGB/Hex values. I do have one suggestion. Add the option to use custom backgrounds using a folder like the logo folder. Of course you can't change the background image colors but changing the opacity would be good.