You can upload just the latest Hog 3PC to update your Road Hog. The XPe image is the full operating system and Hog 3PC. You can choose to upgrade this if you wish, but it is not required.
You should update the Hog 3PC when not in the middle of a show, but before you start a new show. The XPe you might want to update on occasion, and sometimes we might require you to upgrade it. It is really a choice for you and your users. If you ever need to do a recovery of the system, you can do that from the desk, but it will only restore to the last XPe image. SO if you have updated your Hog 3PC only, then do a restore it will revert back to the older Hog 3PC....
