This isn't research. This is from experience...
I was running JB4 on a bone stock 2013 335is with DCT. I went from an "integrated" unit to ISO running 16.hex to 24.hex every increment along the way. I had the best success with 18B.hex
Once you mod your car with DCI, DP, FMIC, bigger turbos and new exhaust, you really need something like the JB4 or Cobb or Proceed to compensate for the changes you have made. But for the 335is, BMW has already made some of those changes for you. I had nothing but problems since day one - guinea pigging myself on a daily basis. Since I remained stock, the JB4 didn't really help much. In the end, the JB4 wasn't able to clear the codes faster than the ECU was able to create them.
Once removed, I was finally able to eliminate:
( ) Low throttle oscillation
( ) Hard shifts between gears
( ) Shift lag in D-AUTO
( ) Incorrect downshift rev-matching in SPORT-SPORT
( ) No boost on downshift till upshift matches OEM
( ) No correct "overboost" operation
( ) No correct Launch Control operation
( ) Engine Malfunction - Reduced Power
( ) CAN lag between JB4 and ECU
( ) Being locked out of JB4 entirely once overheated while you are halfway between
Phoenix and Flagstaff with 3/4 of a tank of E85 mix and your car doesn't know what to do!!!
Whatever...I still stick by my original impression back in April 2013: