It won't make any difference to our software if you run FSX in Administrator mode or not. What will cause problems is if you enable also another flag in the "Compatibility" page. Just use run As Administrator, and keep everything else off.
However, it's wrong that you HAVE to run another add-on in Administrator mode, it means that add-on is bugged, or not designed to support proper UAC rules which were in place since Windows Vista. All our software works normally, regardless if you run it in Admin mode or not.