Michael,
The site you referenced is most elegant in its design and performance.
I selected about 500 points in a test area I was fairly familiar with and exported the gpx. I inspected the gpx output file with a text editor and it was flawless. Impressive!!!
Being new to Chief Architect I had to grope around a few times with the gpx import process, but I finally knocked it out and rendered a decent surface. Next task is to double check a few reference points with my altimeter to build a little confidence with GeoPlanner/CA. I also took a screen scrape of what appears to be 1 foot contours out of the CA topo page and superimposed the lines on a Google Earth aerial. From what I can see and what I know of the land, it came out rather well.
Thank you for the assist in helping me find that tool!
I greatly appreciate you taking the time to help!!!
Bruce