Product review (5 stars): Perfect for it's purpose but....
My cabinet maker found it to be a bit bulky for the size and depth of our cabinets. Which are standard depth and go all the way to the ceiling. (No greasy dust catcher on top of my cabinets) The liner was going to cause the vent cabinet to stand out disproportionately more than the cabinets themselves. I preferred not quite as obvious an incline and did not want a "chimney look". This way it has a more subtle, seamless appearance.
So he installed the vent or power pack without the liner. The liner would be useful for catching gease spatter etc, but after sealing and protecting the wood thoroughly, it will be easier, or at the very least, as easy to clean as the liner would have been.