Hey curlyjocelyn! I've tried the Lush Caca Noir, my hair is dark brown, so obviously no dramatic hair color changes (it is darker though). I've also used traditional Indian henna on my hair, and I only get reddish highlights, since my hair color is already dark, again, not much I can do about it. Personally, I prefer natural henna, because my experience with the Lush henna is mixed: I do like how my hair feels after I've used, but it is really hard to remove from my hair :\
The first time I used it, I tried to wash it off with conditioner only, as many reviewers suggested. My hair felt oily, dirty, and disgusting; at my next wash (right the next day) I realized I hadn't been able to remove it all.... afterwards I washed it off with shampoo and it was fine. But I never had rinsing problems with natural henna.
What's your natural hair color? If auburn is the color you want, your natural hair color will influence what color you get from henna (so it is a good idea to do a strand test). In this page they have many mixes you can make yourself: Henna for Hair: Dye hair with henna, indigo, cassia .... safely, beautifully!