everyone's body is different. there was an article earlier today about losing weight with the same premise.
soylent should be sorta like those the soda machines at the fast food places, cept instead of mixing dr pepper and coke, you could get an extra dose of chicken squirt instead of soy squeeze
But many, many people (esp vegans) argue the opposite. The FDA, after years of avoiding an opinion, finally settled on 34-56g/day RDA for protein.