Obviously this is going to have to come down to GM decision, but...
The issue I see is that you have to remember that even when a cyber-limb has a smuggling compartment (of any size), the limb still needs to function. This would significantly reduce the reasonable size of the compartment and it would clearly depend on the race of the owner. Where in your leg could you fit a whole loaf of bread without removing important muscles, tendons, bones, etc? The theory here I suppose is that the cyber equivalents could/would be smaller, but you still need "stuff" in there for your limbs to work, and the location of said "stuff" is probably also important (ie - cables need to allow the proper direction and freedom of movement).