My birds get ONLY FF as their main feed and it's available free choice from sun up to sun down. My birds do NOT over eat it and they don't eat less and less every time. I save about 10% over my dry feed bill. And the birds don't even go straight to the feed when I let them out in the morning, not even the chicks and mamas. They go to the grass and hunt worms and eat greens and make their way back to the FF when they are ready. It's true we don't always eat yogurt.. but we also wouldn't always eat cereal either. I don't know if you will actually save $ feeding it out like a treat. I can pick it up out of the trough and drop it like a treat and my birds all go crazy even though it's the same exact feed that's right next to them. It's about perspective... they think it's a treat if I'm serving it up.

Also chickens don't have nearly the same amount of taste buds as humans do.
The amount they eat on any given day is relative to a lot of things, not the least of which is weather. On rainy days my birds will lick clean the same amount that might have more than half left on a sunny day.
So, I feed ONLY FF and on occasion I toss out dry feed as treat! They still get whole nutrition instead of candy bar corn kernels. They have access to free range lushness all day. And I'm so pleased to see the ravenous chicks pass the feeder and head for the field first!
Anyways, I do understand what you are saying and we all have different experiences. My chickens find their food just as well as any chicken eating a dry ration and find it the same as they would any other dish of feed.
Do you mind describing these "stomach issues" please? So I can see if I notice what you are talking about. The only thing I have noticed is that they burp more.

I would think filling up on dry feed and then drinking water that expends it would cause more problems than filling up on a wet mash.. if I were reasoning it, and I am. But I am here to learn as well!