Took a closer look at my system. My head is a fixed-in-place porta-type potti with an integral tank that I guess holds 5 gallons. It is vented overboard and has a discharge line that goes thru the bulkhead to under the v-berth. There, the pump out line connects to a tee in the discharge line. The other side of the tee leads to a manual gusher-type pump and then to a 1/4-turn ball valve, and then to the thru hull. So, similar to Kito's boat, except for the type of valve. I looked carefully in the v-berth compartment for any signs of a prior tank and couldn't find any.
The reason I though the pump out line was not connected is that the only time I tried the dock-side pump out, nothing came out. The head pumps out just fine manually, so I think the vent line is not plugged. I'm sure that when I tried the pump out, I also tried opening the gate valve between the toilet bowl and and the holding tank below, so to be sure the tank was vented. I will back flush the pump out line with water to make sure it is not blocked.
Fortunately, the system doesn't smell, except in use, when one opens up the sliding valve to discharge the contents of the bowl. Then you get a good whiff of the contents of the holding tank, which is pretty foul even with deodorizer. AS long as the door to the v-berth is kept closed, there is no smell there, fortunately. My only incentive for considering a marine head is to eliminate holding tank fumes from going into the boat when the head is used.
Dalliance - in your old set up, where was the manual pump - in the v-berth compartment along with the holding tank? The compartment looks pretty tight for that.
Cheers,
Gary