There's only one download and without a hash there's no upgrade path... so is this just new installs? I don't have hardware laying around, but was interested in upgrading 9.2.1.8 to 9.3B as all my data is backed up.
Shouldn't be doing that... Worth checking the bugs database to see if anyone has reported that yet and creating a bug report if not. You could also try the latest nightly of 9.3 at http://download.freenas.org/nightly/x64/.