After two days of figuring out the best way to downgrade to 10.9.2, i'm happy to report that everything looks OK so far. My solution:
Boot your MacPro in Target Disk mode while it's connected via Thunderbolt or USB 3.0 to another Mac.
Format your MacPro's drive
Install an earlier version of OSX
Upgrade to 10.9.2 (Very important - MacPro 2014 won't boot anything earlier than 10.9.2)
Upgrade to latest Creative Cloud versions
This will be quicker than waiting for 10.9.4 - which may not solve any issues anyway. Stick with .2 until Yosemite or .4 is confirmed to be compatible.