Ed, the thing is, a VW trans is supposed to be drained and refilled after 300 miles according to the Bentley manual, which I'm thinking is the same as the factory manual. Nothing has changed as far as the metallurgy of all the gears and bearings, so I'd stick to that.
Jim, I'm not advocating for dino then synthetic. Cheap oil for break-in miles is common sense to me. And the synthetic Valvoline I use is available anywhere, and just happens to be synthetic. I notice much easier shift action when it's 40-50 degrees out, before the engine and rolling along warms the trans.
I buy the Valvoline Synthetic for the same reason I buy Valvoline 4 stroke motorcycle oil for the engine. It's available EVERYWHERE.
If Subaru doesn't recommend changing, that's fine. It won't hurt if you do.