OK. I shouldn't bitch too much about a free program/web site.
I've tried ICE with just two images and even taken out the barrel distortion beforehand from each image, tried all four (PM1, PM2, PM3, and RM) stitching methods, but no luck, the joined image is "blocky" and mismatched across the entire match path, there does not seem to be any blending across the match path.
I also noticed some of these same artifacts in the Photosynth I've posted. It's hard to see unless you blow it up and step across the tiled imagery.
I have several other pieces of SW that I'll try, and if all else fails, I can always do it manually in Photoshop as a last resort.