I am taking out my old tired heads and am considering those Sealand Vacuflush models. NO...not the vacuum flush toilets that require a sealed seat to work! The actual Sealand brand ''Vacuflush'' line. They work similar to a airplane head. I would appreciate anyone who has real experience with living with these. NOT A Sealand SALESMEN! Also, any advice on the best head you''ve come across.