for cas3+ if need downgrade 10 minutes and seems safe.
make sure you have proper power on the car
cas4 F10 – ok (new key)
cas4+ F10 – ok (new key) isn from org key or dump DME
fem/bdc F31 – ok – reset mileage, change isn, change vin, make keys with oryginal key and with dump from DDE
cas3+ E60- ok , downgrade and make key with isn from org key
Did a 2008 E60 CAS3+ had to DOWNGRADE it took about 10min and programmed key successfully
Cas4 can only be done by reading DFlash from Freescale cpu then load into programmer software and generate key. It can no ne done by obd.
You need xprog or vvdi prog to read the dflash.
BMW Multi tool
I use multi tool to downgrade the CAS on table by CAS plug and 12V, then i make key, downgrade process takes 30 min, making key takes 1 minutes the whole job is 31 min without opening the CAS.
I can do CAS4 all key lost as well with Multi tool, but u need the help of a DME, 10000% Success, job done on table, ADD key by OBD. I m using Dialprog, done 1 all key lost and 3 add key , not a lot of testing but so far so good.