I was thinking that myself as I read Grappelsaw's post. Steep crossovers seem to suffer more from phase issues. Part of the reason the Thiel crossovers are so damn complicated (in addition to the sloped baffle).
And I further suspect you need fairly exotic equipment to identify it is happening. I don't know that you would pick up on it audibly, unless you could A-B between phase distorted and not phase distorted. The "ambience" setting on my boom box sounds pleasant and is using this technology to do so. So, it wouldn't necessarily sound unpleasant, but it would not be a faithful reproduction of the source (which is my goal unless using old receivers).