Air versus air
Back when I worked for a yacht manufacturer we installed Webasto units in a boat that normally had a Marine Air type system. We were on our way to the Miami Boat Show. The Webasto unit failed and had to be replaced 3 or 4 times during the show after the crowds went home. The yacht manufacturer never considered a Webasto unit again after that. Customer service, however, was excellent. But the failure rate was comic.