How to ensure a stolen MacBook Pro Retina is useless to a thief?
The security you’ve enabled probably won’t deter the theft of your laptop.  Most criminals who get the opportunity to snatch a laptop will take it no matter how useless you can make it with encryption and firmware locks.  

Why?


Ignorance of the criminal.  No matter how much Apple advertises it, the common thief won’t know until they get it back home only to find they got a brick.  Then it will probably become a frizbee.
Salvage value.  Although useless as a computer, the machine becomes a “donor” for the parts including the screen, trackpad, keyboard etc.  even the logic board can supply someone with a ton of components to be used in logic board repair


Your strategy should be data protection, ensuring that no matter where your computer ends up, you have quick, secure access to your work product.  Enabling remote wipe is invaluable in making sure your data stays secure.  

I would also look at insurance coverage for that expensive device.  Many credit cards cover theft.  There are also 3rd party insurance coverage from companies like Safeware