Automated vs Manual NDU

Toasters,

What's your preference for non-disruptively upgrading a switch based
ONTAP 9 cluster - automated NDU or manual (rolling) NDU?

Happy to hear of both positive and negative experiences, if any.

The cluster in question consists of 3 HA pairs so the automated
upgrade will default to rolling.  The general recommendation is to use
the automated procedure but there are concerns about lack of control,
especially in the event of issues.  Each HA pair in the cluster hosts
critical prod workloads.

No access to a test cluster so there isn't much opportunity to build
confidence in the automated procedure ahead of time.  I am aware of
the ability to pause the automated upgrade.

Leaning toward manual at the moment due to lack of exposure to the
automated process.

Cheers,
Phil