Doing my FF vs APS today, I just found constantly that the first picture of a series is always brighter than the other one.
In Lightroom it is equal to 0.05+ adjustment. This is not a big difference, but you can see it in clear sky shot with you have the two beside.
Another finding, long exposure at night ... I don't know clearly what this come from (I was suspecting the frequency of the exterior lamp) but in this night shoot you can see that the white car not in a unique white trace ... but a kind of slice ... :