not that much difference in noise
1DM3 vs 5D high ISO test
but
D3 vs 1DM3 high ISO test
Canon dethroned on noise and focus, filling up the market for an extra 1000 Euro
D3 12MGB full sensor / 1DM3 10Mgb 1.3crop(focus problem) / 5D 12MGB full sensor(focus ?)