SLaswell hit the nail on the head with people's objection to the brand. Nobody's saying they are crap regs. We are saying please don't insult our intelligence by claiming the component materials are equal or better than apeks, Poseidon etc. I think I clarified that at least 4 times in this thread.
Unfortunately people have to do more homework than just looking up the country of manufacture. Just looking ay the car manufacturers. In our extended family 2 chevies of different models had major failures at 5000! and 30k killometers. Both are made in N.A. My friend had 2 wheel berings go at 60k kms on his Ford. We now have a recall on a GE dishwasher that can catch fire due to faulty heating element.
I would smile at anyone saying N. A. Produced goods are better that the rest of the world.
There are only a handful of companies that actually make scuba regulators - Air Liquide, Sherwood Selpac, Beuchat and Tabata are four of the largest. None of them are in the US or have US based manufacturing facilities.
Regulators from most major "brands" are designed by the company (such as Scubapro) that then outsources the production under contract to company like Tabata that has the specialized production equipment to make the design. Given the comparatively low volume involved it's a lot more cost effective to outsource production that to develop and maintain the production facilities in house. The quality that can be achieved is much better than the company could do on it's own in house equipment and the production cost is lower as the cost and upkeep of that specialized equipment is spread over a much larger number of regs made for several companies.
Other companies may also license the design and sell it under their own banner. For example, Halcyon currently markets four Scubapro first and second stages with minor cosmetic alternations, but made to the same specifications and QA tolerances. TUSA (Tabata USA) has also rebranded several Scubapro regulators, no doubt part of the manufacturing agreement with Tabata.
Still other companies license designs with or without minor changes, but with varying QA tolerances and specifications. This is where it gets sticky. There is no such thing as a free lunch and while you will find the same OEM design sold by two or more manufacturers and find them priced at widely different prices, generally speaking, the lower the price point, the wider the tolerance ranges for the parts and the more the performance will vary. I've always been impressed with the Dive Rite regs i've worked on and the quality has been uniformly high. I can;t say the same thing about most of the very similar looking regs from other manufacturers. Those regs sell for less, but that's because they are not made to the same tight tolerances.
The same thing happens within brands as well. For example the Scubapro R series second stages have never had particularly high QA standards 295 and performance varies a lot. If you've got a bit of a dog, you'll usually find you can't improve it without swapping out parts to get tolerances that stack on the right direction. In contrast the QA standards on a G250V are very high, particularly in regards to tolerances for the spring - and it has to be as that reg lacks a micro adjust feature. Try making the same design with low QA standards and you're going to have some issues.
When you apply all the above concepts to inexpensive clone regs you'll find that, given adequate acceptance standards (which is not always the case), they will meet the minimum specifications that are required by the manufacturer. However higher specifications cost more money and better performance and tighter tolerances on parts all mean a higher cost to the company selling the reg, and a higher price to the consumer. What it means is that I can swap out parts on a high end Scubapro or Aqualung reg and have a high degree of assurance of being able to tune it for peak performance that will be at a level well above a similar design that sells for a lot less money after the same parts swap as the QA standards on the lower priced reg are commensurately lower. Out of the box, that may not mean much, after you add a few years and a few hundred hours of use, and replace a few parts, it starts to become clear which reg you'd rather own and dive.
You do, to a very large extent, get what you pay for.