Greatly enjoyed reading this review. I'm really tempted to try a Curve now!
I've used my unlocked Treo 680 for a year now and I'm generally quite happy with it. One thing that struck me is that you missed the Treo touch screen and that the Curve did not feel as good in your hands while calling.
While the touch screen can get you to the function you want quicker than using the arrow keys, I find that during calls with my Treo pressed against my ear some of the menus will be activated. Usually it's the Bluetooth menu that goes on but sometimes I get a beeping window asking if I want to dial another call.
This is a minor annoyance of the touch screen that happens mostly in noisy settings when I press the phone hard against my deformed ears. I guess they don't call me dumbo for nothing...