The average American diet contains about 15 grams of fiber. A single serving of Soylent contains 9 grams of fiber. (As per http://blog.soylent.me/post/74770956256/soylent-1-0-final-nutrition )
The sudden increase in fiber will cause many people to become very gassy. It may be worth considering adding a warning about such an occurrence. Perhaps a suggestion to possible solutions (such as Beano, or other digestive aids) until the body can adjust to consuming the recommended amount of fiber.
A few months ago, I went from an “average American” type diet to the recommended amount of fiber. The flatulence caused any room I was in to be unbearable, until I started taking Beano.
Hopefully my body will adjust and I will be able to stop taking the digestive aids.
I expect some people would try Soylent and then stop soon after due to the gas issue, if there is no solution ready for them.