Love this colour combination. I've never seen purple nagabakama before, though I have heard them referenced as being worn exclusively by unmarried women. Wish I could see some documentation to back that up, though.
Noble ladies in the Heian era wore gorgeous silk robes. The color combinations, graduations and patterns were important and often referred to the seasons. These are some typical combinations. Pine Tree colours - All season wear (because the pine tree is evergreen and unchanging)