Have done small to medium institutional rollouts of Firefox in different orgs, some of which were on top of a Linux base and others a Windows base. Windows deployments include Firefox in the base image and configuration is managed with AD and Ansible. Linux deployments manage configuration with Ansible. The preinstalled browsers were removed or disabled.

All users received an orientation and were informed that Firefox is the only approved browser.

Firefox was pinned to the desktop and taskbar, usually with the name "INTERNET" as the web browser is commonly known here.

The number of support tickets was very small. Usually if a user reported a problem with the web browser, it was a page that was also broken in Chrome or some other network issue.

Users reacted positively when they saw that there are no ads in Firefox. uBlock Origin was preinstalled.

Without ads and tracking scripts the web browser is massively faster, which also was perceived by users.

If there is any initial resistance to Firefox, it usually melts quickly.

The only bother has been the frequent UI updates to Firefox, which occasionally cause frustration until we apply a new configuration to revert whatever fresh horrors Firefox designers have birthed. With ESR, these problems are less frequent.

I hope this Firefox Enterprise freezes the UI to the classic "tabs look like tabs" aesthetic, maintaining the option of vertical tabs.

I wish this was true. At my org we had to add Chrome to the base image because otherwise we get so many tickets/calls about it even though we provide it via an internal software distribution service that any user has access to. People like what they like and are very resistant to change.