I am less convinced. If the GMan nabs you, sees you are using a tool which heavily advertises a hidden partition, and coincidentally your drive has a large unused block of random data - they are unlikely to be fooled.
If your security concerns are about governmental intrusions, then you have a security need that no single tool can resolve anyway. You need to address overall behavior and habits, which are likely to include things like not keeping sensitive data on machines that can be easily accessed regardless of the use of encryption or obfuscation.