This is our standard studio scene comparison shot taken from exactly the same tripod position. Lighting: daylight simulation, >98% CRI. Crops are 100%. Ambient temperature was approximately 22°C (~72°F).
Sony DSLR-A700 vs. Nikon D300
Sony DSLR-A700: Minolta 50 mm F1.4 lens, Aperture Priority, ISO 200
JPEG Large/Fine, Manual WB, Default Parameters (Standard), Self-Timer (auto MLU)
The DSLR-A700 and D300 have identical vertical pixel count, the only difference being the D300's 16 extra horizontal columns (obviously Nikon has a slightly different interpretation of 3:2). A quick scan down these crops indicates that there's very little difference in absolute image quality apart from perhaps slightly more low contrast ('texture') detail from the D300 and a very slightly more conservative approach to sharpening.