I should also note that an FPGA will not perform as well as a custom ASIC (such as a GPU) in terms of speed, power, or price (in significantly large quantities)

I should also note that an FPGA will not perform as well as a custom ASIC (such as a GPU) in terms of speed, power, or price (in significantly large quantities). An FPGA can be a very good options for moderate to low volume applications. You are correct with your description of a potential FPGA application. I would say it could rival or exceed the performance of the GPU solution.