Apparently all have their criteria that results in a choice of one transmission type over the other. Having extensive experience with both manuals and automatics and appreciating the pros and cons of both, the choice for the M3 has already been made after driving M3s equipped with both MT and DCT.
Criteria based on personal preferences.
1. Which demands greater driver involvement?
2. Which is more reliable?
Aspects such as marginally faster shifts with an automatic, seamless shifts, are not compelling reasons for me to opt for DCT. Why not? Because the miniscule per cent of time the vehicle would be driven when that fraction of second quicker shifting with DCT would be tapped simply gets dwarfed into relative insignificance by the magnitude of driver involvement (two feet + two hands) that is constant.
While some DCT owners haven't had the experiences of others who have had the dubious pleasure of dragging their M3 repeatedly to service centers for this or that bit of work thanks to DCT acting up, I have absolutely no desire to make any trips to a service due to transmission ailments. For those of you that live near a service center, it isn't that much of an inconvenience, but for some people who aren't exactly within an hour's drive (one way) to a service center, the DCT would be a royal pain in the a$$ thanks to warning messages advising to take it in for service as experienced by some owners.
Regardless, even if DCT were ever to achieve the reliability, maintenance free level of the "antiquated" manuals, item #1 of my criteria would still present me with a huge obstacle to overcome. Yes, I realize that automatics appear to have a hold the future, and that too could be another reason to go the manual route in 2010 since the manuals could be gone in the near future.