Most people are windows users and won't be able to download just an image of the first partition and dd it onto the stick.
Should have a button on the desktop to "Update USB Stick" or something, can start with a shell script and make it more usable later.
Hopefully the dd can be done while the system is running.
dd can be done while the system is running but the system becomes unusable and needs a hard reboot. Need another solution. Have and idea to try out.