So, I moved enough to buy an S9 into BCH at around 4pm GMT, hesitated slightly, went out, came back 4 hours later, BCH gets added to coinbase, wait another little while wondering what the hell is happening. BCH moons. I put the S9 order through.
30 minutes later, they're sold out, and BCH is crashing. My order price was locked in.
Worked out that I got my $2800 S9 for about $1700.
Lessons learned:
1. Bitmain KNOW releasing an S9 batch will pump BCH, as people scramble to move coins into BCH to complete their order.
2. Bitmain probably have a big bunch of S9s left. This was almost certainly NOT them running out of stock! Coinbase added BCH, there was a massive sell off of BCH, and only after that did they announce they were out of stock. All within about 3-4 hours of each other. The order makes me think BCH dump was Bitmain cashing out all the BCH they'd just received from the S9 batch.
My theory is this was a well co-ordinated and quite clever pump and dump by Bitmain/Roger Ver/Coinbase.
I will be waiting to see what happens between now and March 2018.
Probably re-selling my $1700 S9 for insane profit on ebay the day it arrives. They currently sell for around £4000 GBP ($5400), which is part of why I think $2800 isn't that unreasonable for Bitmain to price at. The real money they make is from BCH market manipulation.