So If it was shrunk down to 45nm it would energy wise (optimal) result in a saving that result in about ~2 Watt chip, that does 1.25Gh/s.
Guess I wasn't that far off, when I estimated 1Gh/s for a single usb powered Chip based on a 45nm design. Still estimates, but at least an estimate I could believe.
More precisely, scaled to 45nm, Bit Erupter's chip would give 1.96 Ghash/s at 2.5 Watt.
This is 787 Mhash/sec and slightly better(!) than my prediction of 700 Mhash/sec for BFL's ASIC.