Hey! One of the authors here. I will do my best to provide some responses, but it's kind of late here.

- I find it weird they didn't really point out any down-sides, possibly because it's a corporate blog and marketing wouldn't let them.

Not at all the case, we had some bad but felt the post was kind of long so they ended up edit out. No one but us reviewed the post first ;) Actually didn't even really notice all the negatives were gone until it was mentioned...

Here is the negatives we edited:
"
It was not all positive. Finding a smooth way of working took a long time, and we lost team members along the way, presumably at least partly because they did not enjoy this. Personality differences became painfully obvious, and a lot of time was spent talking openly and honestly to each other on how to stop rubbing each other the wrong way.

Taking on new people is both easier and harder in this setting. The bonus is that they will come up to speed with the work a lot sooner. The drawback is that you have to redo the personality resolution dance before work will run smoothly again.
"

- No time to think. I find I solve solutions by thinking about them, and I can imagine mob rule would lend itself to less thinking and more doing (fastest solution that sounds half-right gets done first). Similarly…

This was actually a focus of a retrospective today, and we do see this happening sometimes. We agreed today to try to be more aware of it, and for people to speak up when they feel it is happening.

- Biggest personality wins. I'd worry that whoever had the largest personality would drive everything, leading to people being disengaged. Especially when it comes to engineering / structural decisions, if that person thinks they know whats best you're not going to have the chance to try something (and maybe fail) and grow as a developer

This was only the case for the first few weeks, then as we point out in the article: "Interpersonal issues and friction had to be resolved. When interpersonal issues happened they get brought up much more quickly. In a ”normal team” when there are these types of interpersonal issues they are often allowed to fester. People who have issues only need to deal with each other for limited periods of time, so they just grin and bear it. This isn’t really possible inside of the mob because you would go completely insane."

So this ended up being actually the opposite effect in the long term, dominant personalities were addressed and we all grew as a result.

- No personal space. You know, maybe it's because I work from home, but sometimes my fiancee messages me a video of a cat being cute, and I might just take 2 minutes off working to watch it, because I'm a human being and not a sack of watery meat sacrificed to the gestalt. I could imagine it would be very awkward to do anything at work that wasn't explicitly working, which sounds pretty suffocating to me.

This is indeed something we struggle with, and we bring it up a lot. People are allowed to leave the mob as often as they choose, but sometimes it feels like there is a social pressure to stay. All I can say is we try to be aware of it, and one of our working agreements is to "remind each other it's OK to leave the mob"

- Constantly bringing people up to speed. Maybe this is actually a good thing? IDK, but I think if some people are faster than others, or people wander off to make a coffee or whatever, or come in at different times, or leave at different times, you may spend a lot of time going over the same decisions and working through the same problem spaces over and over again. This could be a good thing, or it could be OK that some people know about component X and some know about component Y and there is little overlap.

Not sure I follow this one :P

- If anyone from Meltwater is reading this I'd be interested to know if you had any problems (these ones or other), because it sounds like-- ignoring the first month-- this plan has no flaws. Which seems hard to believe.

It's definitely not been all smiles and roses, and we have struggles like any team, but we also all agree that this has been an amazing experience and well worth any negative effects we've seen.