Good morning, Sam!
It's easy to update to a newer release, but be aware that iFly probably sent you the latest "stable" release. The incremental updates (.sh files) are mostly untested beta releases, and may have bugs. However, you can always change back to an earlier .sh release, but I wouldn't perform an update the night before "the big trip" without good personal testing. It's also possible to have several .sh files on your Windows/Android computer (not iThings) and update "on the fly" (see what I did there?) if you have issues in flight that you think are update related. Once you learn how, updating via .sh files takes about 20 seconds and a reboot.
Here's the update files:
http://updates.stratux.me/builds/
Here's some instructions on how to update (and other good info):
https://github.com/cyoung/stratux/wiki/FAQ
Basically, you click on the .sh file you want (newest is at top) and it will download to your machine. Remember where the file was stored and connect the same Windows/Android to the Stratux wifi, open a browser (I.E. Chrome), and go to the website 192.168.10.1 You'll be at the Stratux Status page.
On the dropdown menu (top left) click "Settings"
Scroll to find a box that says "Select System Update File..." and click on it. A window will pop up allowing you to navigate to the file you downloaded. Double-click on that file to select it and you'll be back at the "Select System Update File..." box, but now the text has changed to say "Install System Update File...". Click theat box again and the update will proceed. It says give it a minute but sometimes it's as fast as 20 seconds and sometimes it's longer. The important thing is to not interrupt the update process. When it's done updating, it'll reboot the Pi and you're ready to go. It's not a bad idea to let it boot up fully for a minute and then reboot again.
Good luck!