I do every day. It's pretty awesome, I recommend trying it. D's CTFE and templates are really really nice to use. I can write very low-level high-performance memory sensitive code, controlling everything, but the code can still be beautiful with great compiler checking. It can confuse my C++ brain sometimes, though, and then it's great to have someone to consult with (e.g on the D forums).

Key stretching is critical for password-based encryption, and gpg's s2k options are vulnerable to GPU acceleration. Command-line tools to encrypt with bcrypt/scrypt are common and may be a better option.