I'm curious about Soylent as well. I wonder, however, if it provides the same kind of "emotional satisfaction" that real eating does.
I know that, after doing a number of long fasts, that I begin to crave chewing on something, and that I have a difficult time feeling emotionally balanced when not eating as I normally would.
An interesting concept though, nonetheless. The website does not list the full length of ingredients, from what I can see, so it would be important to confirm that it doesn't come packaged with a long-list of preservatives and chemical additives.