Loooking toooootallly osome dude!
How many antennae in the back is he going to have?
It'll be cool if it kind of like, have two more going up its back. Like eldar wraitguard/lords with their spines.
Or else, have it splayed out horizontally... ooo I donno too many things that could be done to the back me thinks!
The gun still seems to be top-heavy, but I think that's because there's a huge cavity missing where the arm would go. I'm sure once you added something hefty below it will counter-weight against the gun. But still, osome osome osome.
sj