From what I gathered they are more like the Free Flex pro 15s without the connecting plate. But besides that, I don't know much of a difference between them and the Peak 15s. They have different AFDs and the Free Flex has a higher vertical release pressure compared to the Peak 15 (won't release vertically as easily, but the same sideways). This is due to the racing design of the binding. Also these Mad Flexs have more metal in them than the newer designs but are still pretty light for a strong binding like this. (See the link I posted above and TGR forums say the same)
I got most of that information off of the Tyrolia site.