I handle all the deployment processes. I am the core manager for the entire infrastructure, so I manage and deploy everything.
I consider how many users and gigabytes we expect on the network and try it on a test network first to validate before actual deployment.
Just my core team members manage the whole deployment, so that's enough for us.
Migrating the old one to the new one took around a month because we have many rules, and the new Netgate was quite different.
From the maintenance perspective, it is not difficult at all.
While configuring or maintaining pfSense, we had high CPU usage on one firewall, but the GPAC subscription provided a good response. The support team was helpful, and we resolved it in a few hours. So, we had good support because of the support subscription.