Looks really good man. I'm glad someone finally stepped out of the box. I think the top tube height is good from my point of view.
As far as it being top heavy, yeah it looks like it is now but once you tie in a exo that will not be an issue.

Like CoRunner said Don't build your mounting points too strong or you will be replacing a frame. When I t-boned that dude a while back. Had the Smitty-buit bumper brackets not collapsed My frame would be toast. It didn't even scratch the powder coat on the bumper but the brackets were almost paralell to the bumper.
It is kinda a median between strong enough and too strong.