[Qmulus]

Yes, the different immobilizer part numbers have different functions. M535 only means that the modules have radio remote control. When you swap modules you must use the same part number if you want to be sure that everything works properly. One issue is that the early modules have the antenna terminals in the blue connector, whereas the later modules have a separate RF connector. Early ones also do not have the luggage compartment releases, like you have found. There are a few other differences.

The BIGGEST issue with swapping all the modules to get the car running is that unless you got the VIN number from the seller, you will not be able to do any programming on the immobilizer or DME in the future, like adding keys or reprogramming the DME. Basically, as far as Porsche's internal system is concerned, your car now has the identity of the car you swapped the modules from. If you don't have that VIN, don't lose your key as you won't be able to get another one unless you replace everything again...

The best way to replace immobilizer (IMO) is to get a new or used immobilizer of the same part number and have the info swapped over from the old immobilizer, or have get it programmed by a dealer if it is new. There is no need to replace everything, and while a dealer can't match a used immobilizer to your car, it can be done. I do it all the time, in the case of the module being severely water damaged or even burned. The only cases where you can't is if the internal data has been corrupted, which is only about 10% or less of the time.