I have only heard the PSD2002 once but it sure sounded pretty nice. And I do not doubt that the price/performance ratio of that driver is the best out there (piezos apart). But I might be willing to spend a little more to get an even better driver. As I said, I can get the Beyma's pretty cheap and the JBL 2426 even cheaper. (Second hand, that is. JBL pro parts are just too spendy over here. A 2226 for example retails for around USD $650 a piece!). I am leaning towards a wooden horn for the 1'' driver, your conical Pi horn for the mids and a JBL 2226 at the bottom.

/Magnus