We have now been using our Nature's Head, which operates the same as an Air Head, for three weeks. I find it easier to use and more discrete when others are on board. However, the biggest vote of confidence comes from my wife, Beth, who happens to be a nurse. She loves the ease of use and the simplicity of keeping things clean.
We carry the liquid waste container in a zippered shopping bag to the on-shore public toilets to empty. This has proved easy and has attracted zero attention. We have not had to empty the solid waste container yet, but do not expect complications.
I will offer some installation and use advice for those considering the composting toilet. First, be sure to get the unit as level as possible so that the liquid waste is directed where it is supposed to go. This will ensure that there is no accidental combination of liquid and solid wastes: the combo is sewage and it what smells. Second, do a simple wipe of the "bowl" with vinegar after use, particularly around the liquid waste holes, in order to eliminate any potential urine odor.
We have chosen to bag our toilet paper in order to extend the "life" of the peat moss. This may be a learned procedure, but we use zip lock bags to keep the issue contained. One can deposit the toilet paper into the unit, but the paper will not decompose at the same rate as the solid waste and will more than likely reduce the time between emptying by half.
In three weeks of usage, we have noticed absolutely no odor. Moreover, Beth has found the entire "marine going" process to be easier, cleaner, and less concerning. I anticipate that our visitors will have a bit of "on-boarding" shall we say to the use of the composting head. However, since it can't be technically clogged, I suspect most will silently offer thanks that the embarrassment of that is avoided.
Anyway, on Harmony, we are very happy with the change and find the simplicity of use and lack of sewage on board to be tremendous.