Mattias you are 100% correct, there is NO WAY the bottom petal can lift when you have a very soft petal on the top. Ron Chinoy (RD Dreams) was the first person to strobe and film reeds in action. He found s as rpm rose the bottom petal barely lifted and the top petal flapped about uncontrolably.
The dual stage petal has long been ecilpsed by a VForce.
I'd disagree with that last part.I've run both and prefer the Boyesen pro series carbon's hands down.
You have to remember that as the top(softer) reed opens far enough the tension increases to the point that it is in contact with the bottom reed and the two are working as one at higher rpm.
They don't necessarily flow any better but simply regulate better throughout the rpm range.
Stock reeds are set from the factory as either high,mid or low tension depending on what power characteristics the engineers are after.
I've always found that as a rule of thumb,I've ended up jetting down two sizes on the main and pilot both after intalling the boyesens.
Better spread of power and better mileage.What's not to like?