I was wondering about the downsides of making my EBS storage encrypted. Why isn't this option the default? I encrypted my current EBS and everything seems to be working fine, performance wise I am not experiencing any slowdown either.
There is not downside as such but sharing across accounts will required extra steps since snapshot created from EBS will also be encrypted either you need to copy again with shared key or choose the shared key in the initial stage itself.
Apart from default master key, we can choose different key for encryption, so by default you can't always encrypt and start with master key.