Yes it makes sense to move to 3.11.3
The release has features and bug fixes which should be useful to your cluster.
However, if you are planning to use GROUP_BY, UDFs etc.
Please be cautious about the performance implications it may cause if not done with suitable queries.
I am not aware of any specific doc to perform the upgrade.
But, the steps you are following for upgrades looks fine.
I think the `upgradesstables` step is not in correct place in upgrade sequence.
I think upgrade sequence should be:
- drain and stop
- backup configs
- install new release
- review config updates (patch existing config)
- start Cassandra
Not to forget: Perform upgrade on one node at a time.