I can only support hector's well formulated arguments. I'm very enthusiastic especially about JForex API but such incidents as last weekend and unfortunatelly still ongoing really cast a lot of doubt on Dukascopy whole service.
I'm a software engineer myself and I work routinely with systems with at least three environments (production = live, training = demo, development, often with 1-2 additional ones) for much less crital applications with much fewer users. I can't believe it's so hard to install another server for demo users and have developers work in their own separate environment. It's copy-paste

(OK I know how hard configuration management can be)
The point here is that Dukascopy can't assume that demo users will accept unannounced and prolonged down times - you're destroying all the goodwill with this !