Okay guys.. I found a video comparing HTC Desire against a new Samsung Galaxy.. the HTC's touch tracking shows the jumpy/choppiness that I found in the EVO. I guess it must be an HTC thing.. Watch in the beginning of how the colored circles on the HTC screen jumps and struggles to track the finger. This is exactly the behavior I found while dragging a web page in the browser and panning/zooming photos in the gallery.
YouTube - Samsung Galaxy S - Multi-touch.mov
Well for the record, iphone was out of my consideration a while ago.. EVO was my choice by default (reluctantly given the poor camera and the lackluster UI performance from my short play with it). Now having explored more information, I think it might just be an HTC shortcoming. I'm sure the EVO is a great device for folks who are not bothered by those issues, but for those who are, the EVO's shortcomings are difficult to live with.