Imaging and soundstage

Yes, but what is behind the listener can be even more of a factor than the distance. The distance will often determine what should be there.

It seems that the consensus is the listening chair should be a minimum of 4 feet from the back wall.

Since your topic is imaging and soundstaging, you might also try moving your speakers around a bit. There's an Allison rule that seems to work quite well for speaker placement. That is: (All measurements from the front center woofer driver)

Middle distance squared = shortest distance multiplied by longest distance.

Implementing this rule along with toed-in speakers so the tweeters and midranges are pointed directly at the listener's ear could be an excellent starting point toward obtaining pinpoint imaging and 3-d soundstaging. And perhaps even the ending point.

-IMO

Stehno:
Maybe you could put that into plain English for those of us who are equation-challenged.
Use an example -- with real numbers, please. This sounds interesting, but I don't 'get' your drift