What I find odd, is the post above, from someone who appears to be speaking on behalf of Matrix, yet doesn't identify themself, in an attempt to "clear up a few things", a reply that came very fast after your OP, (especially considering it was a Holiday weekend) yet you still haven't received an official response.
I appreciate you taking the time to write your responses, and agree that serial numbers should be on every unit. No matter what argument one may use for not having them, how hard is it to use them? I mean, really. C'mon.
In this day of buying online, and having to do your own research, and figure out which reviews actually mean something, and which ones you should ignore, having these kinds of threads help in making an informed decision. And I'm all for giving any company the benefit of, not every product that goes out the door will be perfect, and mistakes happen..., but not communicating with a customer in a timely manner, even if it's just to say, "Hey, I got your email, but I'm crazy busy, but I will get back to you by ___", is frankly, unacceptable. Especially when we're talking about a product that's obviously intended to pair with one of THE top modelers (it's shown with an Axe Fx III right on their website), made by a company that's known for exceptional professionalism.