Thanks, very interesting!
Quality is comparable, actually at certain shots SA at 8MP is maybe a more consistently detailed, 15MP is sometimes a little noisier and I don't see much quality edge.
Where this can be very useful however is shooting large resolution full 4:3 frame SA images, as on stock we're limited to 8MP @16:9
. It makes sense to give the full 4:3 option, and I'd love to see some 8MP vs. 20MP SA comparisons, if you have the time.