Howard!

It IS impossible for simple anatomic reasons! Instead of bringing up *fairly* successful examples ( like Dave T. ) the "principle" in it is this: Whoever you are you will be able to transmit force/energy from the arms to the instrument more efficiently with the handstrap connection than with the thumbstrap/fingerplate concept and energetic bellows reversals ( necessary for bouncy playing) demands comfortable and efficient "pumping".

Speed...picking single note playing of scales or chromatic runs ( which is the best indicator) of "speed" as such.. you will find nobody able to execute the same speed as with the english using any other of the common concertina systems. You CAN do it - and even faster for some passages - with an accordion though but the cause of that is the option using a "flyng hand" as with the piano. Concerning instrument "speed" in general the two-hand-superiority ca be illustrated by a hammered dulcimer or vibraphone as well.

Concerning choice of instrument I absolutely agree. One funny thing remains as a puzzle for me however - the English ought to be more suitable for the typical "Irish" idiom than the Anglo... but tradition got its own pathways, not necessarily rational ones.