Effectively, the further back a fin is the more it will add to the grippy feel when sailing straight, particularly at lower speeds. With the 2010 setup the big fins could only be placed forwards and then some extra area was needed to keep the board performing. With the 2011 you have so much more options. First you can run the big fins in front like before, but move the rear fins further back because of the adjustability of the slot boxes. The makes a huge difference and moving the rear fins back and forwards really makes it possible to fine tune compromise between straight line performance and feel when turning. Then you can
run the big fins in the back which generally give a looser (and less drivey) feel when turning, but also good straight line, particularly if you move the rear fins backwards. And rocker and bottom as such is also like before rather "powerful" for good upwind work. So I don't think you need to worry about it.
If you already have the Quad76 and like how the drivey feel in a bottom makes it easier to generate speed, the I think you should stay with the Quad for 2011. You will have that same feeing, but also the ability to tune it towards a "softer" quad setup and as a super loose twin fin.