I guess the easy answer is that it gives you another option to empty the tank when you are cruising. You only need to be outside the 3-mile limit for this to be legal.
Ooooh, now that would be a problem and pretty much kills your optionsI remember, this past December, looking for a pumpout in Annapolis since we had a full holding tank. Every place was shut down due to the freeze. We'll just leave it at that
The primary difference between the macerator and just going for a pump is that the macerator will pulverize the contents of the tank. This is both good and bad. The good part is that it greatly decreases the amount of time for any "materials" in the tank to biodegrade. The bad is that if there is anything hard in there, such as popcorn kernels, you can damage the blades of your macerator and end up SOL, pun intended. Macerators do have a large electrical draw (20amps+) but only while you are running them, and to pump out a 20gal holding tank you are talking about 90 seconds or so.
By option, do you mean to plumb directly from the head to the thruhull? We have a Raritan SeaEra toilet, which uses a macerator to pump to the tank. While grinding things up may reduce the time it takes for shtuff to break down, it's not instantaneous! We're set up as Doggie recommends, so we are always using the tank. The aroma that wafts back to the cockpit when under sail certainly eliminates the possibility of someone discretely ducking below for a quick comfort break.Just get - DIY if you have to, trust me nothing more romantic than someone going down below, few pumps and ewwww and the **** hits the vent while sailing (within legal discharge zones). Having the option is priceless.