First off, I agree with Azezel about his points. You definitely want the Mantle Of Ophelia. Drop a few seraphim and get an eviserator. I would consider taking flamers on them instead of inferno pistols. If they are sitting back, you aren't really popping vehicles anyways, but those divine guidance flamers can but a huge hit on infantry.
Also, if you have an Inquisitor joining the sisters squad they are no longer faithful and thus can't use faith points. Just remember that. Also, not sure he is worth the psychic hood. Most casters have a leadership of 9 or 10. So you aren't likely to stop the powers with the hood. You are probably have about the same chance using the Sister's natural 5+ invulnerable to psychic powers.
How do you plan to deal with armies that can outrange you, like guard and eldar. Sister's make a great static army when their opponents have to come towards them. When they have to move up and attack, they can have more problems, I would consider that fact when you build an army list.
Also, if you have an Inquisitor joining the sisters squad they are no longer faithful and thus can't use faith points. Just remember that. Also, not sure he is worth the psychic hood. Most casters have a leadership of 9 or 10. So you aren't likely to stop the powers with the hood. You are probably have about the same chance using the Sister's natural 5+ invulnerable to psychic powers.
How do you plan to deal with armies that can outrange you, like guard and eldar. Sister's make a great static army when their opponents have to come towards them. When they have to move up and attack, they can have more problems, I would consider that fact when you build an army list.