For those who asked, the Marine Elegance generally uses less water than the SeaEra, particularly if you spring for the Smart Switch computerized, programmable control. That's where the extra cost over the simple pushbutton switch shows its worth; with its flexibility - particularly if you have kids onboard. The high-end switch has two basic flushes available: 1) the Normal flush, which has (3) vacuum bursts to evacuate the bowl, each lasting about 2 seconds each, with additional rinse water coming in after each burst. That is the average, although they can be programmed for other time durations, both longer and shorter. In the Normal flush, the toilet uses a little over a quart of water. 2) the Water Saver flush. the Water Saver flush only runs one vacuum burst, and uses about a pint of water. The Water Saver flush is used primarily for #1, and the Normal flush for #2.
In addition, the programmable Smart Switch has two other buttons on it. Add Water only, and Empty Only. These must be held in; they are not automatic. The Add Water button will only stay on for a maximum of 7 seconds, and the water flow will stop. This fills the bowl about 2/3 full, and no more. It is a safety feature that is buit-in, for kids playing with the button; they can't overflow the bowl. The Empty Only button must also be held in and it simply empties the bowl, without bringing in any water. This is useful if rough seas are expected and you don't want water sloshing out of the toilet and onto the decking.
Most SeaEra heads are operated by a simple push button. You press it in, it flushes. You release it, it stops. So the water useage is controlled by the operator and how long the button is held in. Average water use runs somewhere around 2 quarts, give or take... Raritan offers an optional timer for the SeaEra head, too; but it isn't a standard item and must be special-ordered. Also, it isn't fully programmable.
Another nice feature of the Marine Elegance is that all of them have a built-in trap to insure that water will be retained in the bowl between flushes. There is no additional vented loop requirement to retain water. No other Raritan toilet comes standard with this feature. But if you want to empty the bowl - rough seas coming up, press the Empty bowl button and hold it in; you'll pump all the water out of the bowl.