- I have both sets and can offer my opinion of each:
Sportsways Pros - The manifold system is superior to the USD system because of the fool proof O-ring seals between the center valve and the two tank valves. The twin tanks ride perfectly on my back and position my double hose regulator perfectly too.
Sportsways Cons - Because they are 1880 psi, they have more steel and are heavier. I wear 2-4 lbs of weight with these tanks and a 3 mm wetsuit for neutral buoyancy at 20 feet. At 50 ft I wear no weight belt with these tanks and 3mm wet suit.
USN 38s Pros - Being 1800 psi and therefore less steel, these are lighter than the Sportsways to carry and more buoyant underwater. I wear 10-12 lbs weight belt with a 3mm suit at depths to 20 feet. At 50 feet and deeper I wear 6 lbs weight belt with a 3mm suit. I can even dive these tanks with just a swimming suit and I don't sink due to excess tank weight.. The twin tanks ride perfectly on my back and position my double hose regulator perfectly too.
USN 38s Cons - None. For me anyway. I enjoyed restoring the tanks and they have become my favorite tanks to dive with. I refill them easily from other tanks. These and a set of yellow USD Twin 38s (also 1800 psi) have identical buoyancy characteristics and they are a close 2nd in my favorites column.
Above left: USN 38s. Center: USD 38s. Right: Sportsways 42s
Interesting Side Note: The Sportways tanks are 38 cf at 1880 psi but they were advertised at the 10% overfill capacity and referred to as "42s". The USD tanks are 38cf at 1800 psi and were originally advertisaed as "38s". The USD ads were later changed to the 10% overfill capacity so they could call them "42s" ... to compete with Sportways I assume.