The Rotex in RO mode will work just fine. In terms of speed, the ETS-EC 150/5 would be quickest -- depending on the quality of the veneer, though, particularly how thick or thin it is, you would want to be careful about burning through the surface with the 5mm stroke. You actually don't face as much of a danger burning through the veneer with the Rotex in RO mode (even though it has a 5mm stroke), because the pad rotation is not as aggressive as the ETS-EC. I only sand veneered sheets with the ETS 150/3 now, but I'm overly cautious.
In terms of grits, I tend to start at 150, but as Tom already pointed out, you could even start at 180 if the sheet is already well sanded.