Firstly, Driving in DS does not necessarily mean u r over-stressing the internals. As long as sensible driving techniques are maintained eg No persistent redlining, inefficiently maintaining high rpm above 4k when the most efficient torque curve is up to 3k rpm (anyway, it's quite breathless after 4k rpm n u r just wasting fuel), no jack rabbit starts and sudden acceleration, hard braking, stop and go traffic - u get the drift.
The DS mode gives u a more aggressive map within the limits of the BMW and there is nothing to fear or avoid using it. Find yourself a good stretch of road, minimal traffic, B roads etc. Of course, don't switch to DS mode on stop-go, heavy traffic or leisure cruise where the D mode is most efficient. Otherwise, give it a good run in DS, your car will love you for it, it blows out cobwebs and soot from our 'dirty' diesel. Overtime, you will find the car more responsive and willing.
I serviced mine at 5k km too but realize that with the adaptive service sensors, I can run down the intervals fairly quickly and there may not b a need for out-of-pocket services. I also find that the engine oil is 'more fluid' and less darkened with regular spirited runs.
Any drawbacks then? Well, just about one and probably only one, higher fuel consumption. While i use to avg about 7.1l/100km, I get between 7.8 to 8.1 if u use DS mode frequently. The trade-off is driving joy.
And lastly, BMWs are made to be driven