Well, the Union and C3 guys I talked with last season all said the Charger is absolutely the stiffest binding that Union makes and sells. I guess they could be wrong, but somehow I doubt it. It definitely was the stiffest Union binding I rode. I don't know that I would go so far as to call it the stiffest out there, but I absolutely would say that it is the stiffest in the Union line.
Well, the Union/C3 guys do not really seem to be consistent or in agreement on what their stiffest binding is (based on this
In any case, the Chargers might be very well be the stiffest Union binding (note that I did not claim otherwise), but they sure as hell are not the stiffest bindings in the market.