Great post greff, it almost makes me nostalgic of my electro-dynamic days. I am pretty sure I would have got myself a p1u (or even a p1 which could be found used from the dealer at about 700usd at the time!) if it wasn't for my going to the stax route...
I also found it very organic and natural, a perfect complement to keep the hd800 under control. Somehow, I imagine a bit dark tonal balance with the hd650 but never tried though.