I have bought a Radon (re-batched Cube frames for bike-discount.de, if I'm correct) hardtail. Not the prettiest bike, but a proper work horse. Good frame and excellent parts for the money. Only used it a few rides, but very happy so far.
Radon are not rebadged Cube bikes, having had a good look at the Radon (hardtail) range there are significant differences between the two (drop outs, mech hanger, down tube gussets...)
The full sussers are totally different designs too.
However they do appear to be as good value as a lot of the newer brands on the market, saying that Cube have been around since 1994 IIRC.
Cube have been in the UK for about 6 years IIRC, the brand just keeps going from strength to strength, I've not found a bad review on any of their bikes yet. The Cube Attempt road bike recently won a Cycling Plus bike test, since the test was published the bike has almost sold out for the year in some sizes!
I think that the big brands like Specialized, Trek, Giant etc who splash out a lot on marketing hence higher prices are maybe also are relying on brand loyalty so customers don't really mind paying over the odds for their new bike from their favourite manufacturer
Brands like Cube, Ghost, Radon, Focus, Rose, & Canyon can provide excellent bikes with superb value pricing due to a smaller marketing budget and maybe being less greedy than the mainstream manufacturers seem to be
The mainstream brands will need to book their ideas up on pricing sharpish as their market share will start shrinking once the consumers realise that you don't have to buy a big name brand to get a brilliant bike and that they've been paying over the odds just because of the name on the downtube of the bike