I think there is more than one company that makes them. Lite made them a few years ago and had a recall issue . Im not sure about Viking but it appears to be the same type of tank.
They are expensive and not popular because the weight is in the propane more than the tank itself. If I remember correctly the base weight difference empty was minimal.
The advantage is being able to see the gas level. In a single tank set up I can see the advantage but in a dual tank set with a change-over regulator, it has lass impact as well as bang for the buck.