Usually updates within an iOS major version or within a Stage Traxx feature version don't cause new bugs. Only big iOS updates like 15 -> 16 or feature updates in Stage Traxx like 3.5 to 3.6 tend to introduce new bugs.
Doing a backup before an update will not help with bugs caused by an update as restoring a backup will always use the newest iOS and app version available.
So my advice: Use two devices. Update one and see if that works fine. If not, you have your backup device with the old version. If everything works fine, update the other.
If you don't have upcoming gigs, just update.