I have a platinum Gameness and Atama double as well. I feel both are extra heavy, like wearing a suit of canvas armour. Once I sweat, they both get baggy, heavy, and provide a great workout while training. Unfortunately, they both don't fare too greatly in the heat of summer, but make excellent winter training gi's. The Gameness collar was thicker than my Atama double, IMHO. I wish they both didn't have the back seam. They rub my spine when I'm on my back and it can irritate.
I had a Koral single which I really liked. It was form-fitting, light, and tough. I was looking at getting the Atama Mundial gi because it looks like a beefier version of the Koral.
How thick is the material on the Mundial? How does the collar thickness compare to the others? Have you trained in it yet? If so, does it hold its shape well after sweating heavily?