I like mine
I just went through the exact debate and spoke to someone who already had a pair and decided to get them myself. I drive a jetta sportswagen and it was important to me that maintain my fuel efficiency as best I could while also knowing I would have racks on the roof 100% of the time.
The racks are not silent, but theyre much quieter than typical racks. Initially mine were whistleing a bit and I called whispbar and they were committed to figuring out the problem (which we did) and the bars no longer whistle. I can hold four boats easily on my room with a stacker. The rubber in the middle of the bar and theyre flatness are more valueable than I thought, as they hold they boat upright on their side much more easily and you dont deal with it sliding flat (which means its easier to load a boat when theres a smaller amount of bar space available if that makes sense).
Fuel efficiency is great! I am getting 45mpg (diesel) when riding with just the racks (no boats) on the roof.
Hope this helps!