Personnaly, i preordered Black 32g (from geekbuying), after reading, i changed it to black 16. They refunded the difference.
After the first batch was received by Geekbuying, mine was not sent....
So after talking with presale support, they changed it free for 32go blue (without asking in fact if i wanted blue one), but they didn't charge the price difference.
That's pretty cool, and they told me they send the blue one as soon as they receive the first batch.
Well after many mails, still no shipping, so i canceled. (Should have bought from Willgoo like i always do for my pre orders...)
But i contacted GPD directly on aliexpress (they sell directly), and bought it ther, shipping was done on the same day.
So for those who don't have a shipping notice, go check Aliexpress, if Willgoo have not enough stock.
Edit : here is the GPD shop on aliexpress http://m.aliexpress.com/store/storeHome.htm?sellerAdminSeq=220915346