Download the latest update and check out the changes since your unit's current version that are listed in the Addendum.pdf. If there's nothing there that is required by your bass player, there may not be a solid reason to update.
On the other hand, if you have any kind of problem with the unit in the future, you may be expected to update the firmware to the latest version by support. Also, you may be required to update the firmware to be able to use the latest versions of the Rig Manager software on different platforms.
If the current OS is from 2018, you will have to install two updates to get it up to date. As per the instructions:
If current OS installed is older than 7.3.2, install 7.3.2 first.
For what it's worth, I have a kemper since 2013, and have profiles on it from around that time that still work. I've also updated the firmware at least a dozen times without any damage to existing profiles. I consider installing via USB the safest option, since you don't have to worry about the connection to your computer going down during the process, for whatever reason.