Maybe it's just me but every reg I have ever had from five different mfg's has breathed a little wet upside down. That is basic physics. Even the one Scuba Pro reg I had did this. Mk16 R 195 or something. The Taiwanese OEM's are often thought of as making simple copies. This from my research and actually speaking with one of the engineers is not true. They have base models that they will sell. I don't know what every one of their minimum orders is but on some goods if you order 500 units you can have your own brand of THE STOCK design. But you can also work with them and specify tighter tolerances, quality levels, different materials, and different finishes. SO just because they look the same does not mean they are. By a long shot. This is true with many industries around the world. My own day job has the same parts for different companies who have different quality and finish levels. For example a washer made from 1/2 inch steel. Same part, same OD and ID, but different levels of finish and tolerance depending on the application. One wants a very fine finish and +/- .005 on the dimensions. That gets cut slow so it's more expensive. Way more. The other wants a rough finish and +/- .060 on the dimensions. We call that a rip and run. A common practice across many industries.
I don't know if DR and SM are made in the same place. But c'mon people the basic outside shape is neither unique or proprietary at this point. And as for WOB on a reg. You can get the numbers but unless you have a machine in your lungs the majority of divers, including tech divers, can only tell in their mind if the Mk30 XL 800 breathes 5% better than the reg that is half the price in this day and age. No one is going to sell junk. Tuning and proper adjustment is where things come into play more. Unless you are regularly doing those dives thousands of feet back in caves and 300 - 400 ft deep wrecks like some of my HOG reg customers are doing I would not worry that much about it.
