DCT issues were solved last spring I believe. Most everyone got the fix with the software. Don't make your decision based on issues you have read, they have been a minority of owners. You need to decide if you want a DCT or a manual and if you don't know, then try something different, in this case a DCT. You know what the 6MT is like, try the DCT and see if you become a convert.
As a point of reference, in the last year I have read several posts from members who went from DCT to 6MT and generally regretted it. I even think a member had a 6MT for like 2 months and traded back to a DCT. I think BMW spent a considerable amount of time setting the car around the DCT given that the GTS is in DCT only.
Personally I love it to the point of never wanting to drive another torque converter automatic ever again.
08 GT500 convertible red package (Black w/ Red stripes) /Ford Racing Exhaust /Cold Air Induction 560hp
10 Porsche Cayenne GTS Black w/ Black Wheels 408hp
11 M3 Silverstone w/ Silver Novillo Leather /Tech /Premium /19" /DCT /Ipod 414hp