At these prices, S3 are clearly the SUPERIOR choice, in ROI and quantity. These consume 20% more power as well. They must lower prices to be competitive.
This is a small initial batch production. S3s are mass produced.
But, here's the math:
T1-RBOX
@40 units:
$645/800Gh/s = $0.80625 per Gh/s
@100 units:
$615/800Gh/s = $0.76875 per Gh/s
S3:
(.66 btc * $588) / 441 Gh/s = $0.88 Gh/s
It's also likely that they will hash at 820 actually, on average, and proper cooling will push it to 840. so the price per Gh would change more:
645/820=0.7865853658536585
615/820=0.75