It could be used to power a ouple of USB LED lamps and a couple of Korg SQ-1, for instance.
What I do not understand is the limit to 1000 mA, when the PSU3 is able to provide 2000 mA on the +5V rail.

Check this:

Now, given that the gauge of individual conductors in a ribbon cable is going to be rather small...28 ga is fairly typical, as can be 26 ga...the given maximum safe amperage (sometimes called 'ampacity') is 1400 mA for 28, 2200 mA for 26. YOU DO NOT WANT TO EXCEED THESE VALUES...because it ain't pretty when you do. We're talking electrical fire here, people! Yeah, even at 5 volts!

So the A-183-9 is limited to a maximum of 1A across its four USB ports for that exact reason. Product liability, basically. Dieter clearly doesn't endorse the idea of flaming gear!

I do agree with you that Dieter is a clever person.

I just didn't know that some more juice could turn a module into a flame throver... ;)
Thank you for the precious information.

Worse still, it wouldn't be just that one module. What would happen is that, due to the excess load on the 5V line in that ribbon, it could overheat and catch the ribbon itself on fire. This would then lead to a bunch of cross connections and shorts, leading to circuit damage and more fire. This would, due to the tight quarters inside the cab, catch even MORE things on fire inside of it...module boards, components, ribbon cables, etc. About this point, the amount of smoke coming from any opening would be apparent...but then, given that we're talking about a sequence of events that might take about 15-30 seconds, by the time that smoke's streaming out of the case, everything inside would be pretty royally boned. Plus, if you have no open panel spaces, putting this flaming monstrosity out would be difficult; yanking the power would stop the electrical aspect, but by that point the materials themselves would be on fire.

Some power supplies and/or modules actually do have overamperage cutouts...but not many that I can think of offhand. So, the hard and fast rule is that you have to know your wire gauges inside the ribbons, know your current draws per module, and never exceed the wire's current handling capacity. Doing so gets expensive.

OK, you scared me enough...
I won't buy that module!