The best I've ever gotten at a Chademo on my 85 was 47-48kW. At a very low state of charge, you're limited by the adapter's 125A current limit - you may not even break 40kW. As the SOC (and therefore pack voltage) rises, the total kW increases as the voltage rises (current still capped at 125A). By the time the voltage has risen enough to hit the station's 50kW peak, the car is already well into the taper and started to drop the current.
The car still displays current and voltage while charging at a Chademo, so you can see what's happening. They haven't (yet) dumbed down the charging information display for Chademo like they did with superchargers (boo, hiss). I can collect data from my next Chademo session.
I find that above 50% or so, Chademo is the same speed as supercharging, due to the taper being the limiting factor.