Safest way to get data off of SSD from dead MacBook

Thanks a lot for pointing out my approach will not work. "Running the same macOS release which is also using your same user account" does sound like a lot of work (I am not even sure it is Mac OS El Capitan :-0).

Can I do step 1) and 2) to at least have a disk dump image of my encrypted data, then experiment with other solutions (fixing my MBP or buying another A1502) to get to my data, and in case this corrupts the data on the SSD write back my disk dump image to the SSD to put the SSD into the same state it is in right now?

@Dave Far - How about just giving it ago with what you have not for a system. Unless you have access to a support computer and a few years of time I don't see you decrypting your encrypted data! AES -128 two key encryption is top shelf security!

Transferring the encrypted data to another disk doesn't alter things and is not needed the drive is not writing back as long as you have the correct user account and recovery key. All you're doing is making the task more complex.

You are right, decrypting the data myself is out of the question. That's why I suggested to make a disk dump image of my encrypted data so that I can write back that image to the original/another SSD in case something happens to the original SSD (similar to an encrypted time machine backup, I guess).

Since I have little experience with SSD enclosures and external filevault, I would feel safer if such encrypted backup images via dd worked...

@danj thanks a lot for your references, too.

I also found an extended PDF version Apple FileVault 2: Tips for IT pros with section THREE WAYS TO RECOVER DATA ENCRYPTED WITH APPLE’S FILEVAULT 2 added.

Are you sure that "You would need a Mac system running the same macOS release which is also using your same user account." is a strict necessity?

From the PDF version I found the following:

The only people who can access the data are those who have the account credentials that enabled FileVault on the disk OR who have the master recovery key. (page 3)

Once FileVault 2 is enabled, only the user with administrative privileges that enabled FileVault 2 with their account can decrypt the drive’s contents. In addition, a master recovery key is created during the initial process; users with EITHER of those keys are the only ones who can decrypt the volume and read the contents of the drive. (page 4)

The service is turned off by default to allow end users to perform the initial setup process, which allows them to create a master recovery key. in the event that they become locked out of their account and must recover data via an alternate path. (page 8)

2: RECOVERY KEY METHOD on page 10

@Dave Far - First, if you're so worried about using the case and you have a compatible MacBook Pro that you could swap out the blade SSD just do that! Then you would have direct access to the files as if it was the original system!

Now you could then just copy off the drives data to an external drive sitting in the case (making sure you don't encrypt it in the process.

As far as what you discovered in the PDF version (which I hadn't seen) I can't speak for their testing, all I know is what has worked for me and I did encounter issues using a different user ID.