The longer I work with the program the more I see the problems for those who need more than the progam can provide.

If you include and xampp or let advanced users include their own server, preview will be the same as upload, and the iwzip-format would just be used for backup, so we don't really need the export function for editing, which is like a dead-end-street.

PHP could be coded and tested easily and there are more advantages.
One example: I have to add the same subcategories to all products. What would I do? Edit them one by one within the program? No. I'd rather edit the file xcart.js using find & replace. I'll have to export the files to edit them, but I'll never get them back into the program.