Yes, I own a SWFW SS 3-15. Maybe it's a shitty one (I got if off the sample list) because my Mark 4's glass makes it look like a toy.
Maybe my eyes are older and different than yours... but the MK6 uses the same lenses used in the MK4 so maybe you do agree with me
Not bashing the SS 3-15. It's a good scope for the money. I think you can do better for a little more money is my point. Maybe there are better choices for a couple hundred more than the two I mentioned... I dunno. You tell me. The OP was asking why they're not more popular so that's the issue I was addressing. They're constantly traded-in on the sample list... wonder why?