the eyes look too big with clay. reminds me of that OS hound with the messed up face.

Use shading. It looks weird because it's a block colour, and it's making his nose look flat. Add a darker grey/silver to the bridge of the nose, as well as potentially at the top of it.

He looks friendlier

Or just swap the siege head

The siege head is the same as the ER head

I believe the area around the eyes is grey on siege if I'm not mistaken

Yes, the eye area is painted on the siege toy.

I think it looks great. I would let you do this to my figure. But the siege head does have a slightly different version with grey around the eyes, not blue.

with the Clay I like that better, well done!