Robens are a german company and I have used a robens challanger for a couple of years. Its not the model that is currently on their website but the model preceeding it. From my experience it was fine, a tunnel design in my case, but the weight was over what they claimed and it required almost 20 pegs.
However, it seemed relatively robust and was quite spacious except for the porch which was tiny, really tiny. It may have been corrected on the newer model, and they are using newer fabric also.
I have no experience of the hard-rock model and there is no mention of it on their website, but from what I remember of last years catalogue it was quite heavy for camping if your intending to carry it. But they do tend to be cheaper than the top end brands. It all depends what you what to do with your tent.
All in all I have had a relatively good experience with my robens tent but I am about to buy a new tent and I've choosen the terra nova voyager. Take from that what you will.
