According to two senior AppleCare advisors I spoke with today, it is possible to upgrade your SSD storage without voiding AppleCare, although it is a little complicated.
First of all, if you choose to install a 3rd party SSD, you do so at your own risk, even if you choose an Apple Authorised Service Provider to perform the installation.
Once the 3rd party drive is installed, this drive is not covered by AppleCare, but all other MacBook Pro components are covered. However, should anything go wrong after installation, in order to keep your AppleCare valid you must keep the original SSD. This original SSD must be installed in the MacBook Pro, when it is returned to Apple or an Authorised Service Provider. During re-installation of the original SSD drive, the same risk applies regarding AppleCare not covering damage to other MacBook Pro components, or the drives themselves.
To summarise:
- An MBP with the OEM SSD installed inside it is covered by AppleCare (if active).
- If the OEM SSD is switched for an aftermarket SSD the neither the MBP or aftermarket SSD are covered in that state, whilst the aftermarket SSD is installed.
- However, if there is a problem with the MBP when the aftermarket SSD is installed, the OEM SSD can be swapped in, and AppleCare is then applicable again, even if the problem occurred before the swap was made.
- Finally, if damage is caused during installation of either OEM, or aftermarket SSD drive, then the warranty does not cover such damage.