Last year I put almost 10,000 miles on my single axle TT. The only reason I would go to a double would be higher weight capacity. My trailer weighs 2700 pounds empty and ha a gross weight of 3600. I could see how some people would max it out easily.
I do like the simplicity of the single axle. I have been towing 3000 pound utility trailers for almost 45 years. I have had my share of blowouts/flats. I have never had a properly loaded trailer get squirrely or unpredictable r dangerous. If you have to trailer that is improperly loaded things can go south in a hurry.