Minne, it's not the same as "just flushing overboard".
I was referring strictly to the implication that a composter could be dumped where a holding tank could not. No such place. I bet most do dump their pee bottles where they aren't allowed.
..bring it into the woods and dump it under a tree (which I do)
Let us all know which tree has raw feces under it. Your last deposit is not likely composted at all. Would you drop your shorts and go next to that tree?
....bag it and dispose of it accordingly.
It's really the only good method, IMO. Of course, if it's a plastic bag, that's a shame.
The urine, where legal, can be dumped overboard,
Are you saying there is a place where urine is specifically legal? None I know of. Where you can legally dump your urine, you could flush a traditional head straight into the same water, #2, paper and all.
Also, it's not any more complicated for guests than a pump toilet (with its valves, pump handle etc.). They are really quite simple to use and I've never had a guest screw up.
It's not that it's complicated. It's how well some will take to the idea. Let's not be critical of how people feel about these personal things. I don't care one way or the other, but I am aware that many of my guests would find it objectionable.
If you've never had one on board, it's hard to understand the simplicity of a composting toilet and the advantages.
I acknowledge their advantages, but their weaknesses as well. While I've not used one aboard, I have in camp sites. They are great, when there are no other options. I've also used outhouses, porta-potties, etc, but most would not like them aboard either.
I suppose, if I was alone on a long cruise, I would take to the idea of the simplicity. However, entertaining significantly (probably 100 guests per season) makes them undesirable to me.