If the whole case is sinking heat, that's a relatively decent amount of surface area to dissipate it. If the heat was a problem it would be pretty simple to add additional surface area. The fact that they have not done so would suggest to me that the heat situation is just fine.

That's my worry :-) _just_ fine, or fine by a wide margin? If this thing dissipates 5W as is (without powering USB devices), I would think it gets fairly warm. 2 inch = 5 cm, so area will be 150 cm^2, or 0.015 m^2, or about 300W/m^2 = one third of summer sunshine, radiating out of what looks like a plastic enclosure.