My main issue with FPGA Mining is the cost - with ASIC's on the way... cost price for a single LX150 is about $170, and that will get you ~200MH tops. So unless there is a breakthrough in the software, or a price drop in FPGA's then just look at what Butterfly Labs is offering.... (and take into account you are still looking at another $50 to $100 for PCB's and other components for the FPGA rig... that said I also use FPGA's for rainbow table generation and a few other things so for me its worth it, I cant say that will be the case for people just after a mining rig.
Do you have any idea what the upfront capital, expertise (labor costs), and timelines involved for an ASIC run.
ASICs aren't on the way. Not in 2012 likely not in 2020. If Bitcoin gets as big as Paypal there may be ASICs but you won't see them. Initial runs will be used by private mining consortium to rack up incredible ROI% before releasing them to the general public.