My Grammodes is about 6-6.5" and has ate anything iv'e tried as dithers non-cichlid. He's eaten or destroyed Rainbowfish 2-4", same with SAE's. I haven't tried giant danio's and probably won't, my Grammodes gets very interested when he see's something that may fit in it's mouth. He's also a patient hunter and may wait until lights out.
Still have a couple of SAE's i may try one when it gets to about 5-6" and thick enough not to be preyed upon.
Goodluck you've got some searching to do.