Agree that 3D printers are hard to compare - while reading, I thought of yet another thing that doesn't seem to be mentioned in the article or on the site: speed.

Besides the obvious size and build area, the main functional difference between my very modified Solidoodle 2 and my friend's Rostock Max seems to be how quickly each can produce a print. The Rostock's delta positioning and lightweight nozzle carriage give it a substantial speed edge, but those qualities aren't reflected in most reviews.

Speed vs. quality is always a tradeoff, though, so to collect this spec in a way that would compare printers you'd need a test print and some sort of specific quality standard. You'd also need to tweak each printer's slice/gcode generation settings, since some printers come with profiles tuned for speed and others for quality.