Composting heads make a lot of sense in many ways and I think that the biggest obstacle in the conversion is the thought of dealing with the waste up close. From all I've read however, emptying the chamber is no worse than cleaning out a bucket of mulch. Regardless of the smells and reality of a holding tank inside the boat, out of sight out of mind seems to be the only pro of a conventional head.
I just rebuilt our head, so we'll use it for one more season and then upgrade nest year. We strictly cruise on the boat so far and are making changes with that in mind.