Sultan,
As was mentioned above, I was referring in particular to the EBHA but also the EHA actuators. They are not there to duplicate the entire Hydraulic system services but to power the flight controls and there are some EBHA dedicated to some spoilers. These actuators operate independently of the Hydraulic systems.
Degradation of Spoilers in this case is as you would expect in any aircraft losing a Hydraulic system.
There is a procedure to cover loss of fluid in both Hydraulic systems in the A380 - you get to fly in Alternate law and even have the use of the autopilot for the approach down to 500ft (because of the unusual configuration). And yes, you have antiskid braking, albeit with no autobrakes.
Flight demonstrations? I'm only a line pilot - wrong one to ask.
Helmut,
Only partially true. You would lose the power to the individual actuators, but you would be far better off than a conventional hydraulically powered machine. Depending on where the hydraulic fuses are in, say, a 747 you may lose all the hydraulics under such a circumstance and then you would be in deep trouble. Here, you would only lose some actuators and perhaps not the control surface, since there are two EHA for each aileron.
It doesn't matter which aircraft you fly, you can always pinpoint a weakness that will lead to a disastrous outcome, no matter how unlikely that may be. Just as you can point to the A380 and ask "How would it handle EMP?" you can think up an equally unlikely and silly thing to point at a 747 or whatever.
The 747 is an utterly magnificent design, however I've also found that it is obvious a lot of very clever people have put a lot of careful thought into the design of the A380.
N