Sealand Vacuflush -- satisfied customer
When we got Enchantress my wife told me in no uncertain terms that there were to be no more smelly manual heads. After doing a little research I settled on the Vacuflush, the model that flushes to a remote holding tank (they also made a self-contained unit but I already had a holding tank and wanted to keep that capacity).
Don't remember the cost to the penny but it was about $1200. I installed it myself -- the installation guide is very clear and easy to follow. One tip if you do it your self. Replace ALL the piping y-valves and anything else used by the old system otherwise the smell will remain. Also I built a locker around the vacuum pump and soundproofed it. Not perfect but it doesn't wake us up at night.
The system works exactly as advertised and I've had no problems with it. It uses very little fresh water and power. I winterize it by pouring a couple of pints of watersystem antifreeze into the head and flushing it. Dealer told me it also keeps the seals from drying out.
The head odor has disappeared and there's no more pumping and no more leaks. The Vacuflush, along with the new acrylic galley sink has made my wife very very happy. In fact the Vacuflush is up at the top of my list of best things I've added to the boat.
FYI I have no connection with Sealand, or any marine sales or service company.