I just installed my Conti DWS on a 135i with 9400 miles. Taking off the Dunlop RFTs. I got the 1 size up front and rear with XL load rated tires on the front 225s.
I drove them home today on a real curvey road and with the pressure a little bit higher than I will run 44r 41f the ride quality was equal to stock RFTs. Handling was as noted above. Initial turn in is not as fast as RFTs but its not bad by any means, just slightly slower. Grip seemed good and I could go as fast as I cared to on public roads without any slippage with DTS on or off.
Overall I am happy but I will likely lower the pressure to 41/39F to see how that feels and adjust from there until I get the ride and handling combo I am looking for.
If the mileage on the tires is decent I will be happy. And yes I got them from Gil at Tire Rack