Firstly there's less hoops to jump through. When I edited on my website I had to download the changes from the MySQL database after editing. The new editor makes changes to text files on my computer so no need to download a MySQL dump to save the changes. There were a number of steps when I uploaded changes to Pagoda, now a MySQL upload script is generated from the text files and that is uploaded.
Editing locally is more secure. It was unlikely anyone could or would bother to attack the PHP scripts for editing, but if the PHP scripts no longer exist then they definitely can't. The canonical data being in text files rather than a MySQL database is also more future proof - I did hit problems with incompatibilities between versions of MySQL.
The new editor allows for games being added, and maps game links found by scanning on the fly. The old PHP editor didn't, and I could only check the impact of adding games the next time I uploaded which was once a month in the past. The new editor also checks for not finding scan records we found previously. Before this was haphazard.
Initially I used cookies so the HTML pages for the new editor could communicate with the Sinatra Ruby code. In one or two places this didn't work as I desired so the HTML pages now make AJAX calls to get and set variables the HTML and Ruby code both know about.
Like all good software projects there's plenty of room for improvement. I ought to add the ability to explicitly type the fields in the text data files, doing it implicitly has caused issues with games whose names are numbers. I still need to detect duplicate names better.