Steam has been used throughout history as a means of cooking food. Various design's which are remnant's from the past still are in use regularly today. The Chinese Traditional Bamboo Steamer or the Moroccan Tagine are just two examples.

The main difference between Modern day steam ovens and the methods used over the centuries is the method of how the steam is introduced to the cooking procedure.

In the past the steam was made internally making the need for the oven or steaming container to be raised to a sufficient temperature before the steam is Produced.

In Modern steam ovens the steam is produced externally then introduced into the oven. Eliminating the requirement to raise the oven temperature before steam is produced.

a Superheated Steam Oven uses The same method of producing steam outside the oven compartment. the steam molecules (212 degrees Fahrenheit) are then further heated up to 550 degrees Fahrenheit. Before they are introduced to the cooking space.

So Lets look at the claims of Super heated steam oven's and how they improve cooking

Reduces Calories

This is true but it is also true in slow cooking, and many other form's of cooking, it is achieved by rendering the fat content. with Super Heated Steam this may happen more quickly but it is by no mean's the only cooking method to Reduce fat (even boiling your rib's before you BBQ achieves this)

Reduces Salt

This is also true and it does well but a conventional steam oven will also do this to much the same extent, because salt has a natural diffusing action (likes to balance itself equally all around) as the steam comes into contact with the meat salt attracts to it then is carried away as the steam condenses.

Retains Vitamin C

True once again, Vitamin c is one of many Nutrient's in vegetables that is easily broken down by oxidization (coming into contact with oxygen). This can been seen on a basic level say an apple cut in half will start turning brown, this is the result of oxidization. This is also true in a conventional steam oven.

So what are we left with

Super heated steam ovens can be more fuel efficient due to the shorter cooking time but as you need to use more energy to raise the temperature of the steam this would depend on the amount being cooked.

Because they reduce cooking time they are more convenient.

They do give all the benefits listed above but in comparison to a conventional steam oven the improvements are not that great. compared to a convection oven they are.

(as a side note no type of Steam Cooking will Brown food, most modern steam cookers are combi ovens with a convection componant which browns the food)

To be honest No I doubt I would (there goes my affiliate marketing career). They are being marketed at about $1500 dollars for a good worktop version. If I had that to spare I would buy a good cook book, Take cookery lessons and learn to build a campfire. why?

Because a good cook with a campfire will always produce healthy better quality food than a bad cook with the latest gadget.