TrueCrypt: should I encrypt entire drive or create partition and encrypt that?

I'm debating between these two options that Truecrypt offers. This is a non-OS drive I would like to fully encrypt.

1. Erase all partitions and encrypt the entire drive -

Pros: if the drive gets in the wrong hands, it would just look like a completely raw drive, there would be no way to infer there's anything on it.

Cons: if the drive gets attached to the wrong OS, the OS would see it as a raw drive, and might pro-actively do something that overwrites critical data?

2. Create one single partition and encrypt that -

Pros: the OS will see it as an unformatted partition, and will ask to format it, but it will never format or write anything on it without asking.

Cons: the existence of a partition might be "proof" that the drive is encrypted ?

I could be totally wrong on this, so any Idea greatly appreciated!