I do hope they keep Optimus' mouth. When I watched it in the cinema at the mid-credits scene, I kept thinking Optimus was about to pick a fight with Bumblebee or something. I think he should consistently remove his faceplate for Bureaucratic situations.
Looks great! Did he have the grill on Earth though? I couldn't tell, because of how dark the scene was... Honestly, I hope they leave off the mouth, if this is indeed a reboot universe. I'm not opposed to Optimus having a mouth, but we've seen it in the other films, and even most of the recent cartoons. Bumblebee's face proves you can create a robot that can emote without a traditional mouth.
This is just a mockup i did, they didnt bother making him an earth bot mod i believe, he was just in his cybertronian form.
Did he? I couldnt see clearly from the leaked screenshots. He has his wheels and looks like the orange lights on top of his hood but i couldnt see a grill.
I saw the film, your mockup is pretty spot on. But I would wait until it comes to theaters so you can have closer looks on all the characters before doing more of your scale chart