LargeCoin is as advertised not tested. So take it with a grain of salt it could be a scam (not a very good one if it is) or it could be over optimistic estimate (remember BFL 1.05 GH/s @ 19.8W). Still it is at least plausible that a current gen sASIC could get ~200 MH/s. I would have thought 100MH/W was more likely.
The "Custom ASIC" listed isn't a product offered by anyone.... yet.
Think of it more as the upper limit of what is possible with current silicon. I took the wattage and speed of the SHA "testbed" chip which was used for testing the various algorithms used in one of which eventually became SHA-256 and quadrupled it to account for 2 die shrinks ("testbed" processor was @ 130nm). A 45nm custom ASIC (chip that does nothing but SHA-256 hashing) should be in the ballpark of 500 MH/s.
Beyond that you are only getting more efficiency by making the chip smaller (die shrink). 32nm would be ~ 2x the performance per watt. 22nm would be 4x. 16nm (next gen Intel is look for first production in 2015) would be 8x, etc.
So one could use the "custom ASIC" number as a how close to "perfect" am I metric. I added some caveats to the table for clarification.