FPGA....why....would a bunch of people ask such a thing - they don't really scale up correctly for more hashpower so you are required to move towards asics for more power. Why do you think that is? My only guess is that guys are thinking the next step is to pump a bunch of RAM into an FPGA and somehow convert it over into a SCRYPT sort of thing.
I know a few guys over in altcoin land are working on just such a project, there have been a few pictures tossed around of an FPGA in the center with multiple sticks of PC RAM wired to it. Performance was less than spectacular; although there are energy savings it's a fair way from being worth the cost of the hardware.
FPGAs can't compete with ASICs since FPGAs are basically just a lattice of configurable logic gates, transistors and significant silicon die space is used on the connection fabric that makes them reprogrammable so they will never be as power efficient as something that only has transistors for functions required for the final function of the chip. FPGAs are still great tools for prototyping though.
