Daren – I think that the thickness and material used to make the reeds in the pro 36 is what makes it require a little more air. Thicker, less flexible, requiring more air to make the reed move as opposed to thinner and more flexible reeds that require less air to get them to move….
Interestingly enough, my one true accordion reed that was used to repair the broken original Hohner Pro 36 reed requires slightly more air than the stock ones to get it to move but is also more sensitive to over blowing. Tone is excellent and stable, volume appears to be ever so slightly less. Bearing in mind that this is a modified true accordion reed and not an accordion style reed as discussed above.