As it stands...yes it's a fresh install, there currently is no upgrade path.
It is an entirely new OS platform. Like upgrading from Windows XP to Windows 8...there is no "migration/upgrade".
Some users have reported success in importing some individual module exports. Version 9.4 will continue to be supported for quite a while.
There are a few power users in Untangles forums which might come up with their own migration utility.....never know.
I'm psyched about finally being able to support tagged VLANs. We're doing some cool setups with the Ubiquiti Unifi APs and multiple VLANs.