mtrlt, please enlighten us.
Random tidbit that may be of interest if anyone is unsure whether mtrlt knows what he's talking about. Nova, you mention above that you've looked at the OpenCL source for scrypt mining. Assuming that you're talking about the OpenCL kernel from Reaper or cgminer, hop back into the source, scroll up to the top and examine the copyrights at the top of the file.
https://github.com/ckolivas/cgminer/blob/master/scrypt130511.cl#L2While doing so, don't try to point at the flaws in my explanation and say "it's not x but y & z". Instead start from scratch. Try to remember your audience here.
Frankly I'm genuinely interested in this. I'm also impressed with all these FPGA experts chiming in with their knowledge, looks like lots of people have fully working LTC FPGAs.
This part is true. However, most (all?) of the people that have actually done it have found that the cost/performance ratio is significantly worse than GPU's. This was actually the case for BTC too, FPGA's never had the edge in the cost/performance ratio, only an edge on power consumption. On the scrypt side of things, it's my position from first-hand experience that you'd have to have insanely expensive power or be willing to wait for multiple years for ROI on power cost savings for FPGA's to be worthwhile for LTC mining. We know what we're doing on the FPGA and ASIC development side of things, and yet we have a data center full of 5850 and 6950 based rigs mining LTC.