ISO 1600 raw vs. JPEG
Below ISO 1600, shooting raw gives you some exposure-adjustment latitude, but no clear advantages for noise-reduction or sharpness. ISO 1600 marked the first level at which I could gain a little sharpness by processing the raw, but not without some tradeoffs on grain.
(1/30, f5, ISO 1600, matrix metering, AWB, 18-55mm lens at 34mm)