I originally had a 1M on order, which is of course manual-only. So, I mentally committed myself to a 6MT. I state this, because I know how to drive a stick, and know how much fun that can be.
But, when the 1M didn't work out, and I could choose transmission type in the M3 that I ultimately ordered, I went with the DCT with zero hesitation. DCT makes the car easier to drive faster, for me. I've owned MT cars before. On occasion in the past, I have felt like I'm working too hard to get the car to do what I want it to. You can call me a bad MT driver, I don't care. The DCT gets me the same effective results, with less mental/physical work, and there is no chance of making a mistake, especially if you're really pushing the car.
Plus, I like the technology. I don't care about being "old school", or purist. I want easy, fast, and fun. DCT gives me all of that.