It's worth noting that Val has said we get the same customer service, 60 day test drive and Warranty as main production customers.
I'd call that a first batch to be honest, rather than a test batch. I doubt a company would stand to lose the money from these warranties and test-drives if they weren't sure that these were final, consumer-worthy products. Yes, revisions may be made later on, but many products are revised over their lifetime.
I think we're getting these before release date because he doesn't have to market to get our sales haha. I would guess that the time between PPUs and final deadline is advertising, so that the first day/week/month release sales are as high as they can possibly be. I wouldn't be surprised if Val put these up as 'pre-orders' so that he can say to his investors "Our pre-orders were more than any other headphone EVER". Not that this is inherently wrong or misleading, he's done a pretty amazing thing gathering this amount of interest without a single person actually touching or hearing these headphones before purchase, I doubt that investors will understand 'forum advertising' so translating it to 'calculable pre-orders' was a smart move.