I like your first question, alex, that is what im curious about. What is the difference? Agressiveness seems to be more dependant on the technique, prep and blade, IMHO, but what about the defining key features that sets them apart? In other words, besides an adjustable being able to, well, adjust, :P what else separately defines each one?

I only have an antique gillette adjustable as a reference, so my opinions on what is best is more or less negligible