Batch 6 orders started shipping!
Order date: 2015-11-05 06:53:43
Nothing yet for B4 or 5.
I've just got an indication of batch 4 shipment (11/5 order), nothing re B5 and B6 so far.
My guess, they are being produced simultaneously, hence the monster diff rise.
You're probably right about the diff rise. They are testing the rigs before boxing them up and shipping them out.