I had a DCT E92 M3, now a 6MT E90 M3 and an IS-F.
I can assure you that I totally miss the DCT!!! (on track/street)
6MT feels a bit "cheap" to me since it isn't a perfect feeling shifter (i even ssked it).
Heel and toeing and rowing gears is a diff story.
IS-F tranny is brutal compare to the DCT.