Yes, I have. I should probsbly test them again though, as it’s been a while, and Immich at least has had many potentially significant changes.
LVM snapshots are virtually instant, and there is no merge operation, so deleting the snapshot is also virtually instant. The way it works is by creating a new space where the difference from the main volume are written, so each time the application writes to the main volume the old block will be copied to the snapshot first. This does mean that disk performance will be somewhat lower than without snapshots, however I’ve not really noticed any practical implications. (I believe LVM typically creates my snapshots on a different physical disk from where the main volume lives though.)