All of the AC vents in our house are pretty old and rattle a lot when the AC turns on, so I am looking to replace them. Is there any benefit to doing the slot diffusers over the traditional metal ones? We have a combination of wall vents and ceiling vents in the living room. The ceiling has a pretty good slope to it with the wall vents being on the low end of the ceiling. The "ceiling" vents are below the wall vents (see picture).

For the bedroom, the vents are both wall vents with a big slope on the ceiling, but they are on the high side of the slope.

Google presents a good report on the Pros & Cons.

If that were my house, I would shop the plastic/ polypropylene replacement versions, seek registers that offer more directional options - if needed. If few options locally, Amazon/etc. may have the correct sizes.

Impressive design!

Please post the results someday?