Do I miss out on anything?

[Soft paw]

Nothing missed, in fact you gain extras such as new music (you can still listen to the original music) and upscaled/remastered graphics.

You can play the HD versions with the original musics ?
I have only completed the ps2 versions, I bought the HD version for ps4 a few days ago.

I love the original sound tracks so I am really disappointed they changed them in the HD version.