I looked hard at the Incinolet when I bought my M, but decided to make her legal by adding a holding tank to the existing head. Cost $350 or so instead of $2000.
The biggest reason not to use it was the need for a generator. A "flush" cycle is 10-15 minutes, and the battery draw through an inverter would be 150 amps or more.
A less important reason was the inconvenience of having to use the paper liner. But I wouldn't mind and the girls would get used to it.
The vent would be a problem, because the head is upwind of the cockpit.
1975 32' Flybridge Sedan, twin Perkins 6-354 diesels, 1:1.53 velvetdrives, 16 X 19 props. Merritt Island, Florida