Talked with recruiter then with an Engineering Manager. Last part was a timed response to an example inquiry from a customer. You get in through email and have 20 minutes from the time you get it to the time you need to send them a response. The specific technical question was specific to microprocessor instructions and XNOR's support thereof. Of course I had no idea but sent a reasonable support response which in the end "they" did not like.
My take away was the Manager is really an academic (looking at the profile) without real world experience. Until then things were reasonable, however, dropping a candidate on such a specific question doesn't bode well for a working relationship. What XNOR.AI is doing is pretty cool and would have been fun to work on.
Advice to XNOR.AI have your baseline requirement in the job description and provide advice on what a candidate needs to know so you do not waste either side's time. Have your recruiter ask a candidate "do you know what XXXX is?" When they say "no" then there is no need. I'm rating this a negative experience simply because you unnecessarily wasted everybody's time.