I made this cake last week for a potluck at work - it turned out very well, considering it wasn't
that big a risk.
I substituted the same amount of the Special Dark Cocoa for the usual standard cocoa (3 Tblsp) and it definitely had a more chocolatey flavor. The color was a much deeper red too, but still noticeably red because I went ahead and used the 2 oz red food coloring.
I topped it with my favorite French Buttercream (The Cake Bible recipe using only egg yolks) instead of the cooked Mary Kay icing or a cream cheese icing.
This may become my standard Christmas cake - I so LOVE red velvet!