Have the ability to downgrade
Currently Atlas doesn't support the ability to downgrade major version. I know with Ops Manager on-prem you can do that, which is helpful if you find issues during an upgrade. Would it be possible to get the ability to downgrade one major version on the roadmap?
As of today, if we have issues with an upgrade, we have to build a new cluster with the older version, export and import into the new cluster. That's a much more painful process including the fact that you have to change the connection strings of your applications to point to the new cluster name. And on top of that, you have to take a longer outage to move all of your data between clusters.
The way it could work would be by adding a new node to the cluster (non-voting, data bearing, hidden) which stays on the old major version. It could be configured to stick around for 1-48 hours after the major version upgrade still receiving replication of data, during which time it could be used to roll back with no down time.
After the configured downgrade period elapsed, Atlas would kill the node running on the old major version.
This would be a really great feature and save us a ton of heartache during major upgrades!