I would think that an open baffle would produce poor imaging as the rear reflections bounce around the room "blurring" things.
I use a modified Heil AMT and find that blocking off the rear wave improves imaging. Others have reported similar.
BTW, if anyone wants to hear stellar imaging and soundstage, you are welcome to come hear our creation. I and others have never heard speakers image like this.
We are in Orange County, CA, and if any Stereophile writers are reading this..., come on by! I know some of you live in So Cal.