Yeah , it is tough to beat Thunder Vally's feeders. I have wasted my time trying to build gravity feeders and it is not worth the hastle. The all plastic tube feeders are the way to go in my opinion. they work well and are priced well , too.
The fines do build up in the tubes when using the gravity feeders so yes there are some fines left behind but I do think there is a lot less waste using gravity feeders.
I used a homemade gravity feeder. Darn ***** were hanging from the shoots and raking out the feed onto the ground. Spilled feed never got touched in winter months due to getting wet. Deer spilled a bit but not enough to blow my stack. Also I ended up shooting a hole through one of the shoots trying to eradicate the varmits. Finally abandoned the gravity fed and ended up building covered trough feeders. At least ***** don't dump onto ground AND all the fine stuff gets licked up whenever you let them get hungry. My troughs are wrapped with 2x4s and that stands up to a .22cal better than the plastic or PVC chutes. Whatever works for you.
Do you want a feeder that you have to go inside the enclosure to fill or one that you can fill from outside the fence to keep you safe from rutting bucks?