Thanks guys I think that clears it up.
But.. Max.. if the rear wheel is off the floor how does the engine brake work? 
It works as much as possible, when the rear ha still some force on it. In the past it was common to see the rear hop, jump up and down due to too much engine brake being applied vs the load on the rear tyre, less visible today.
Problem is, front brakes are so strong (and tyres so grippy) that the limit is given by the bike wanting to turn around the front wheel lifting the rear.
Rear brake is to control wheelies, correct mid-turn trajectories and control turn exit (even if, most of this, is probably done better by AW and TC).
Very personal to each rider. In the 500cc era, almost nobody was using it I think (there's a quote of Schwantz saying "the only time I tried it, I nearly crashed. No thx.").
