Tried 4 times now to go on Experimental. Checked that Dayz (experimental) fully downloaded, even rebooted entire PC, but when I click on launch game I see the Steam 'launching game' window for 1 second then it's gone and nothing further happens. I can go back to stable 0.50 with no issues.
I have verified file integrity on each occasion with no issues, so it doesn't appear to be corrupted files.
Have been in conversation with @JCStewart as Issue no. 19087