I saw a DS with side steps at Westover Land Rover in Salisbury earlier this week. Interestingly, it was next to another DS that had a bike on the roof.
My assessment was that getting a bike/on off the roof *without* side steps might be a bit tricky, but could probably be done by opening the doors and standing on the tread plate.
However, if you're thinking of them as purely cosmetic additions, I didn't think they really worked. Perhaps the DS is a bit low to carry them off, compared to say a full fat Disco or Landcruiser.
At least they're just a dealer fit, if I change my mind after I take delivery.
Jon