Hi Melodica-Me,
I couldn’t try out, but an accordion maker told me that you have a double amount of air with bi-directional reeds because even if one reed doesn’t give a note there’s the gap remaining where air gets through. This certainly leads to a huge amount of air when you play chords: a chord of three notes means an amount of air for a chord of six notes! And I can imagine that the volume of the instrument will increase significantly if you have uni-directional reeds.
BTW, I’ll talk to Martin Maurer concerning the reeds you need…
Greetings, Quetscher