I was a beta tester and live a couple miles down the road from the SAI offices. I took analytical chemistry in college with one of the co-founders (Giuseppe). Several of the employees have been over to my fish room. I gave them a bunch of coral and ~80 pounds of live rock to help set up reef tanks.
I know that all of the employees I've met are decent, well-meaning people. I also know that there isn't a lot of experience in running a company, and this definitely shows in all the delays and the lack of communication.
Companies today tend to engage their customers on social media. SAI doesn't. They are very "old school" like this - I'd often go weeks without hearing anything, and then they'd stop by with a new monitor or a new test or something.
This is a new class of product, there are absolutely going to be unforeseen issues. (If you're considering buying this, I would wait for the second generation, as with all other products.)
I will mention that I never once saw it work. I talked with the only other beta testers I have met IRL and he never saw it work either. Based on this, and their complete lack of communication, I sold my unit as soon as I got it. But to be fair to them, I never actually tried a production unit.
If you haven't gotten your unit, you need to email their support about it or call their office. They aren't reading this thread, and they don't care about their [lack of] image on social media.
In order to succeed, they need:
1) The chemistry needs to be valid. Specifically, the equations used to calculate parameters must work in all tanks. I have never seen exactly what equations are used myself, but the readings they provided would drift horribly over the course of a day/week in my reef. They said I was the only one with this problem, and I wonder if they decided to launch without addressing this.
2) The supply line needs to work. I know they switched manufacturers for both the main unit and disks a couple times over the course of the beta. There could easily be supply/manufacturing problems here.
3) The business has to succeed - there is definitely a right way and a wrong way to run a business, and I have seen even the best ideas crash and burn if executed poorly.
I am not convinced that this is the best idea in the world (give me just alk + phosphate + nitrate for $60 a month with no up front charge, and that's a good deal).
I am convinced that the execution could be a lot better here though. I have no idea if the VC money will run out before they are self-sufficient, but if/when people don't buy the product and the company goes under, your $1000 Mindstream will no longer work. That alone should be reason enough to steer clear.