I've never gone that far back, however I'm inclined to say it'll fail due to configuration file changes which would make it impossible to even do a clean install of 9.2xx and import a 9.310 config file.
To be honest however, the farthest I've ever gone back was 1-2 patches to force reload the patch(es) in question.
You're going to need to reinstall from ISO, and use an old 9.2x config-backup, if you want to go back to 9.2. Too many under the hood changes for editing /etc/version to work.
As i as planning to reinstall still i go ahead with downgrade to 9.2 (click on version 9.2 install) and guess what it was same version where i was 9.3x latest version
edit:i am trying to install my 1st dns server on linux and try to configur it with utm but ther was some problem
Just to be clear, the only thing editing the version can be used for is to allow an older Up2ate to work. For example, if you already have the 9.210-to-9.304 Up2Date file and you've already Up2Dated to 9.211, you can edit /etc/version to ' 9.210020'.