No, with the Mafell, it just squares very nicely to the rail. For me, this is enough. If I had to make a hundred fast parallel rips in consecutive, with the Mafell rails, then I would either hold down the Incra rails with my Festool quik-locks, or go with the Kreg T-slot bolts from the Klamp Block Kit (that you showed me, Fidel) to connect to the Mafell rail underneath and then to a hex bolt into the Incra slot.
This system (pictured) sets up and locks in even easier with the Festool guide rails, where the nose of the Incra clamp actually sits in the t-slot rail. If you file the Incra a little, then you could get it to really sit perfectly.
P.S. I haven't had time to experiment, but I would bet that you could also make some killer parallel guides with either the 80/20's or the Bosch-Rexoth rails.