Shannon,
We originally carried Write with the Best years ago as one option for writing for use along with DITHR, and we had many customers use it and love it.

At that time my kiddos were too young to use it, so we replaced it with Igniting Your Writing to use with our own kiddos and recommend to others.
At our recommendation, my own oldest sister used both volumes of Write with the Best with her daughter in grades 6-7 and really loved it. When I was talking about possible writing options that we were considering for our upcoming CTC guide (and we were looking at how best to prepare kiddos for current high school level writing), she mentioned how well she felt Write with the Best had prepared her daughter for high school comp. It made me take another look at the program once again.
I highly value my sister's opinion in this area for several reasons. First, my oldest sister was a high school literature/creative writing teacher. Second, she also has her degree in journalism. Third, she's been a homeschool mom of 7 for over 14 years. So, needless to say I once again ordered Write with the Best at her urging and looked again. (On a sidenote, my sister's daughter went on to public high school and is currently graduating second in her class of 650 students. She excels in all areas but especially in literature and writing).
We have not used Write with the Best with our oldest son. He has done Igniting Your Writing and IEW SWI A and much of SWI B (Continuation). However, we really felt that IEW was sucking the life out of writing for him and turning a gifting of his into drudgery. It just was not a good fit for meeting our writing goals in a way that was inspirational.

So, we've felt good overall about the Write with the Best decision.
With all that being said, one of the beauties of HOD is that you can use your own favorites in the areas of language arts and math if you prefer. Many moms use and love IEW, so you can use whatever you feel is best for your family in this area.
Blessings,
Carrie