Jim
I failed miserably at O level physics, so please bare with me.
My experiences are that 2 " hose and my 1.75" tubed wand outperforms a 1.5" tubed wand and ditto hose by miles, so the theory and figures you've outlined above works in practice. A 2" wand would therefore be even better.
But, on the theory side, surely the air velocity through the smaller bore wand is, or has the potential to be, greater than in a 2" set up. So, would this contribute towards a more positive benefit for the 1.5" wand?
Derek
You can go back to sleep now, if your little one will allow it
Safe and happy wanding
Ken