I really like my Naztech; it is a real nice battery. I use it to power my DR-680, and it provides hours upon hours of power. It comes with a plethora tips, so no additional cable work was needed. Additionally, it has different voltage settings, i.e.: 9v, 12v, etc. In theory (with a Hirose cable from Ted), I could use it to power my SD MixPre as well.
I have no knowledge of the Marantz recorder, so I can't speak to that.