How reliable is Find My iPhone "Erase My Mac" feature?

I recently had a Macbook Pro stolen. I used Find My iPhone "Erase" feature which after two days claimed to have worked. But how reliable is this? The computer had a 500Gb SSD in it, and warns that it could take up to a day to complete the erase. Does anyone know if the "Erased successfully" message is sent after the erase has complete, or at the start of it being instigated by iCloud, as presumably someone could pull the power / turn it off, and prevent the erase completing (if the message were sent at the start)?

NOTE: There was (stupidly of me) no security / encryption on the drive but I did set the passcode when I used the erase feature of FMi

Solution 1:

This macobserver.com article details the procedure that is set into action when you click that big red 'Wipe Mac' button, and how that data could be recovered.

In conclusion...

• A remote lock state limits boot options on the Mac, but can still be circumvented by pulling the drive and mounting it on another computer.
• A remote wipe wipes all internal drives and, once complete, leaves access only to the Recovery Partition.

This Apple knowledgebase article also mentions that

If the device is online, the remote erase begins within seconds (if the device is a Mac, it also restarts before it’s erased), and a confirmation email is sent to your Apple ID email address (the one you use with iCloud).