I use bog standard diesel in my 2.0Hdi, I see little benefit from using "Premium" diesels, only less money in my wallet.
From previous experience of petrol ie regular vs super unleaded I believe that you will only ever see any performance increase if your vehicle is mapped or tuned to take advantage of the higher octane fuel, which I don't think my 2.0Hdi is, but in the case of the tuned Mini Cooper it may have active knock sensing and ignition timing control so that it can eek out a little more power from the few extra octane in the fuel.
Of course the "super diesel" may have better cleaning properties, but I don't see how that will help much.
The Placebo effect is worth mentioning too, I have in the past filled up with Super-unleaded just to "treat" the car to the good-stuff, it just ended up costing me more
And it's worth considering that allegedly lots of the major fuel retailers bulk buy their fuels from the same suppliers, so what's in the pump at your local Tesco might be the same as any other garage down the road. Allegedly.