Wait I'm remembering something....
I think that I remember my teacher saying the following::
If Joe Blogs got ranked first in class assessments, then in the exam he only got 80 but Bob Smith (from same school) got first and a mark of 97, then Joe automatically gets that 97, and Bob gets to keep it (obviously), then everyone else under them gets scaled up.
Now I could have this totally wrong because this is going back more than halfway through the year. So if it is true then there is a definate advantage of coming first!