I'm looking for a DAT file v9350 for testing of a compromised, isolated machine here in our lab. I'm trying to prove that misconfigured settings caused a failure to catch a malicious file, not the DAT file itself. I have confirmed that DAT version 9350 catches the malicious file in question, so I want to do a like-for-like test, our current DATs are 9355, so I don't want to update the compromised machine.
You could setup a daily batch script to download the .zip (and .tar) files from any of these locations for your dev environment. That way you'd ensure to have a collection of any DAT for false-positive and regression testing in the future.
While the info above may not gain you direct access to DAT 9350 for testing, I hope this info helps, nonetheless.