Having owned an 08 ISF and an 09 ISF (and now an 11 M3) I would say that from a dig the DCT M3 with lc is quicker. The ISF is a TOUGH car to launch, especially with the older STIFF suspension. The 11 ISF might be easier with LSD and a more compliant suspension. From a roll, TOO close for my butt dyno to determine. Overall both great cars...
2013 M5 Silverstone/Black
2013 UGR SL TT White/Black