They do mixed-grade classes, and apparently it varies each year what gets grouped with what, depending on their mix of kids. They also seem to be very open to kids being in whichever group is right for them.
Doesn't this mean that if your daughter starts "on dates" (2013) as a kinder she would still be grouped according to abilities, finding herself in a K/1st (or maybe 1st-2nd) classroom?
In which case the fact that she would be even more ahead academically wouldn't matter, right? Making your pro #3 in your original message not that strong?