You've got me watching this one too and on a side note you've got me thinking about the Artix7 FPGA. I'm wondering how well something like this http://www.enclustra.com/en/products/fpga-modules/mars-ax3/ might perform with Scrypt and how well it may scale. For $650 for the starter kit it might be worth me a fiddle.

Again, slightly off topic with the Scrypt but the modules provide an interesting different approach to FPGA PCB's.