I spent several months doing research and finally chose the C-Head for several reasons.
The C Head was invented by a sailor, his intention was to make the entire system out of parts that could be found in any hardware store. Also, it is the only system that comes in different configurations to fit into your boat. On my Tartan 3500 I had to use the model with a cut out in the base because of the curvature of the hull.
And most importantly, the C-Head does not require a vent, so there was not need to cut a hole in my boat.
The installation was easy, but the removal of the old system was awful.
Let me know if you have any questions.