Relevant dinosaur comic. The blog section "What are the haps my friends" below the comic also has some information that might be useful.

As much as I love this idea, I'd be too worried about possible unforeseen consequence to be one of the first people to try it. For example, the importance of gut flora is something that was brought up in the comments to the Soylent blog post that didn't occur to me at all while reading. Even if you can probably get around that, it's just an example of how there are a lot of possible problems you could be completely blind to. As another commenter on his follow up post said:

My overall concern with your idea is that you only eat what is known to be necessary to support life. It used to be that when people set out to sea, they'd develop scurvy because of vitamin C defficiency. You're setting yourself to be a test subject for discovering new vitamins.

Maybe it'd be useful to look up research on people who have to survive on tube feeding for an extended period of time. Of course, there's lots of conflating factors there, but I bet there's some good information out there (I haven't looked).

Also, most of the benefits he described are easily explained as a combination of placebo, losing weight by eating fewer calories, and exercise.

But still, I do like the idea. I bet a kickstarter for something like this would do really well.