I've read through the thread as well as the dark section of Sanahtlig's Elemental Team-building Guide, but still aren't sure who to grab.

I currently run my dark team with Lu Bu, Nyralathotep, Bastet, and Sol, giving me 50% atk down, 30% def down, healing, and a small dark Atk up.

Given that I already have 50% atk down, I'm thinking of getting either getting Amon or Satan rather than Hades (subbing out Bastet).

1. Am I correct in thinking I don't need Hades?
2. If so, between Amon/Satan does one have significantly more utility on solo content?