You'll have to ask Raritan that question
'Cuz they're the one who claim that the pressurized flush water version uses about 1/3 less water than the sea water version. However, it's not too difficult to figure out why: The rate of water flow for the pressurized version is the the GPM delivered by the fresh water pump--about 3 GPM...a solenoid valve simply opens to ALLOW water into the bowl, it doesn't pump anything. Flush water in sea water toilets is delivered by an impeller pump that has to deliver it at a much higher rate of flow to prevent friction from wearing out the impeller. It's the absence of the intake pump that also makes pressurized flush water toilets so much quieter than sea water toilets...'cuz contrary to what most people think, it's the intake pump, not the discharge pump and macerator, that makes all the noise...and uses power that isn't needed by the solenoid valve.And I need to check with Raritan too...'cuz I may be wrong, but I don't THINK the remote intake pump is included with the toilet, but has to be purchased separately. If so, the good news is, you can use just about any washdown pump that's rated to meet the requirements.IMO the remote pump makes sense on large boats that have deep bilges, allowing the pump to be well away from "people" areas...but I dunno where it could go on most sailboats that would put it far enough away from the cabin area to reduce the noise level--which is really the only advantage to it over an integral intake pump--enough to be worth even an extra $75. But hey...it's your boat, your money, and if you're happy with it, that's all that matters.