I just ordered a Zeus 3 at the show. Afterwards I was playing with the demo unit and noticed it was really hot. All the others were the same. Slightly uncomfortable to hold your hand on but not so hot you couldn't leave it there.
The B&G guy said it's because of the way it's mounted and it only draws 2amps max.
Hot means if nothing else power consumption, other than that have to assume it is within its tolerance, however I know people that fly with IPads and they have a tendency to overheat and shutdown if they are left in the sun