I've tried the PVC feeder and found that, in humid weather, they tend to cake if one uses mash feeds. Then the birds empty out the feed in the trough but no feed comes out of the tubes due to the caking.
I use trough style feeders now and I don't have feed waste because I feed wet, fermented feeds. I used to use trough style with my dry mash and just put welded wire over it to prevent flicking and scratching and had no feed waste then either.
Now I use a rain gutter feeder for my trough. Love it!
Not impressed with this...sorry. Too much work involved and takes up too much space. Just utilize a trough with a piece of wire fencing over the top to prevent flicking and scratching and you've got a feeder that creates no wastes.