Here’s the new feedback for VVDI2 BMW on the latest firmware (V6.6.5):
CAS2-OBD mostly good, had EWS tampering fault code with no-start once.. cleared with ISTA/D sync.
CAS3+(+)/encrypted /ista-p version-OBD not good! downgrading bricked a few CAS modules -> much safer by soldering and making key from EEPROM dump.
CAS3+(+)/encrypted/ista-p version is very good if you do it via File make key. DO NOT write new EEP dump back, even if it tells you to. The key will work fine without writing back the modified dump and in fact writing the modified eeprom could brick your CAS in my experience.
CAS4(+) via soldering also very good and safe. you need good skills with hot air soldering and good flux. CAS4 via OBD good but has risk. If damaged CAS, you can fix by programming with E-sys.
FEM/BDC- only tried once on a bench setup.. worked fine with the test bench but never tried it on a real car.