A single FText should not be a problem, but if you’re worried about performance, you can always replicate an ID and then convert it to an FText on the client. With replication the problem is not only the bandwidth, but also the CPU load, because the server has to check every frame if a variable has changed and if it has to be sent again to the clients, and that’s why you have DOREPLIFETIME_CONDITION, Dormancy, NetUpdateFrequency, etc.
If you want to gain more performance, because maybe you have a huge amount of players, you should look into ReplicationGraph and you should see the tricks mentioned in those videos I linked before.
If you want more informations on the Replication Graph, you can watch this livestream from the Unreal Engine Team:
Anyway you can always test your network performance with the profiling tools (like NetworkProfiler):