No, I didn't use treats but it's still a possibility for Hazel, though Hazel's strategy of going alongside when someone else eats is working just fine for her. Just train them first thing in the morning when they're hungriest, they figure it out fast - what to do to get food and how to do it.
It seemed to me they were initially confused about the sudden lack of food available, then afraid of the new situation I was introducing them to, bu the food was a big pull. They were also responding to me encouraging them - they know and trust me to show them good things to eat and what's involved in getting it. Maybe that helps. I kept making encouraging sounds, so they'd go away too wary but come back when I called, and kept giving it a go. I trained them every two hours, and tried to make sure everyone got a bit to eat every time they stepped on the treadle, and I made sure everyone got a chance at it.
On the second day it got bitter cold and I interrupted training and let everyone eat out of their old feeder and my hand too, plus they got the chop veggies.
I looked at the feeder you're getting, looks good for small bantams and small ducks too. They don't really explain the three-stage pin. Does it prop it open a bit so they get used to standing on the treadle but the door doesn't move, or is open and just moves a little? Let us know how that goes! I guess I did it manually, pushing it open a bit and lowering the step, but I introduced the moving door at the same time, I wanted them to get used to it all right away with me there, kind of rip the band-aid off all at once approach, so I didn't prop it open.
I think either method will work to the same end. I don't know if doing it in stages takes longer. It took these guys about two training days - but there's the Hazel factor, who still doesn't open it on her own. It depends on the birds!
Watch the sides, they say those are side guards but if it were me I'd be prepared to put some blocks up.