I have 7, four inch Giant Danios in with my crew. All my poly's are 12" and under, and have not shown any interest in the Danios. I do expect they'll become a snack at some point when either the ornate or lap grows large enough.....
I have never owned giant danios, but if they act like zebra danios, there is a good chance that they will be eaten. When I bought my first bichir I thought the danios would be too fast and big for him at the time(he was about 2.5 to 3 inches). They started disapearing one by one. I've noticed that zebra danios rest at the surface at night, so that's probably when he attacked. Was a stupid noob mistake on my part. Really boosted his growth though