Possible cons of Soylent
I have seen many glowing reviews of Soylent, and many vitriolic naturalistic arguments against it. What I have not really seen is a proper collection of credible reasons why you might not want to try Soylent (that is, reasons which do not boil down to “it’s not natural, therefore Soylent is bad” or “food is great, therefore Soylent is bad”).
Soylent is untested. Indeed, there are apparently trials being run, but I have not seen any data coming out of them (or indeed any evidence of a trial, other than the founder’s word). It is perfectly plausible that Soylent misses out something important - lycopene, for instance, may turn out to be highly beneficial. Of course, various fast-foody diets don’t contain lycopene or whatever anyway. The current fact that no-one has become ill (apart from a well-known and easily-fixed sodium problem) in a diet-related way from Soylent is insufficient as evidence that Soylent is safe.
Soylent is even more addictive than whole food. People often report that Soylent makes them feel really really good for a few days, before they adjust to their new level of wellbeing and “good” becomes “normal”. Then returning to whole food causes them to feel sluggish and generally not very well. On the other hand, some report that whole food becomes extra-tasty, so perhaps it’s a balancing act - switching from Soylent to a good diet may be important.
You hate the idea/you find cooking too fun. Fine, don’t eat it.
It’s effort to test and tune your home-made recipe. Everyone is different, and you might need to make up for pre-existing deficiencies or whatever. As much as the DIY community and Rosa Labs would like it, one size does not fit all, and it might take a while to find out what you need.
There are side-effects of adjusting to Soylent. People usually report gas when starting S/soylent, and sometimes it doesn’t seem to settle down. It seems to be unclear why this issue is experienced, too. There are other symptoms, like headaches (which are apparently usually down to having not enough sodium or not enough water) and bloatedness (which is apparently solved by not drinking the Soylent so quickly).
Expense. There are some DIY recipes which are very expensive. This is often because protein is dear, and low-carb soylents are to be mostly protein and fat by necessity. Too high a fat content is unpalatable, so the expensive protein makes up the calories.