Adjusting speaker positioning. What, if anything, to expect?

Geoffkait, you automatically adjust phase when you listen for the image. Adjusting phase is only important when you have separate drivers such as subwoofers. Think about that. You can move your head side to side and find the exact spot where two speakers are in phase. It is where the image snaps into focus. This of course is the listening position. Phasing subwoofers is certainly more complicated and the best way to do this is by measuring arrival times which requires a microphone and a computer set up for impulse testing. 

Mike, Imaging is the ability of a system to recreate the location, size and depth of instruments and voices. It is what stereo is all about. Whether or not a system can do this well depends on the type of speaker and acoustical issues with the room including speaker placement. Dynamic speakers like yours radiate sound over a wide area creating rather loud early reflections off the side and front wall. Early reflected sound arrives at your ears just after the direct sound from the speaker blurring the image like an out of focus picture. This is the problem with the smaller rooms we tend to put our systems in. Late reflections like off the rear wall (other side of the room) are heard more as an echo. They are also much lower in volume. Late reflections do not blur the image and can make your room sound larger if the early reflections are controlled. Bass is another issue altogether. Anyway there are threads that discuss finding and controlling early reflections. Moving the speaker will change the location of these reflections. Moving  speakers like yours farther away from the walls diminishes early reflections and improves the image but decreases bass efficiency. This is a strong rational for using separate subwoofers and the reason many audiophiles keep their speakers so far out into the room. You can sort of have the best of both worlds if you keep the speakers right up against the wall and deaden the surrounding wall with acoustic tiles or panels. Millercarbon is an old school symmetrical guy and for speakers like yours I think he is correct although there are some like Roger Sanders that would argue with this. With speakers that are very directional like horns symmetry is not as important. My system set up is perfectly symmetrical because my brain won't tolerate it any other way. It also can't stand to see a crooked picture. My speakers are ESLs and they are also very directional. 
Anyway, when you move your speakers around pay close attention the image. Instruments and voices should be very distinct and float in space.
Close your eyes. It should sound like the band is right in front of you. 

onhwy, all that is true but there are many people who don't quite know what to listen for. None of us did when we started down this road. We learned over time. It never hurts to share this knowledge with people who are just getting started. 
Goeffkait, we are never on the same page. Pick your poison.

I also think it easier to LISTEN for the best image rather than LISTEN for the most diffuse sound. Most of us adjust our systems by "educated" trial and error. If you are unhappy with that get a good room control system such as the Anthem or Trinnov units which you can operate via computer programs and you can see exactly what your system is doing. No trial and error.

There are no set rules on speaker placement. There are too many uncontrollable variables involved. The permutations are endless.
Most people just stick the speakers where they fit into the room aesthetically without regard to the sound quality.  While it is true that dynamic speakers usually image better away from the walls I have heard installations where the speakers were right up against the wall and with appropriate use of acoustic treatments sounded quite good. There are certain speakers that you certainly can not do this with such as dipoles and speakers with rear firing drivers. Subwoofers are always better off against a wall or in a corner. 

Pragmas, it is quite true that a speaker's high frequency performance changes as you move off axis. This varies depending on the type of drivers used. Toe-in is important to stabilize the image as much as possible. Point your speakers straight ahead. Now as you move from one side to the other the speaker you move towards gets brighter and the one you move away from gets duller destabilizing the image. If the speakers are pointed directly at you as you move from one side to the other the frequency response of both speakers changes in the same manner resulting in a more stable image. Irregardless the best image is always going to be when you are in perfect phase between the speakers which is usually dead center between the two. 

Yes skyscraper you are correct. With most modern studio recordings the image is based on what the mastering engineer thinks everyone wants to hear by virtue of his own ability to mix correctly and the quality of the system he is using to do this, all of which is questionable. Live recordings can be much more useful in evaluating a system. We all have our favorite records when it comes to imaging. We also know how favorite studio recordings image and know what to expect if a system is set up correctly.
As far as image size is concerned it depends on the type of speaker. Dynamic speakers create a small sound stage as if you are sitting in the back. Linear Arrays or Line source speaker throw a larger stage as if you are sitting up front. There are advocates of both types. A good system is capable of imaging beyond the speakers with the right recording. 
Using an out of phase signal to set up speakers seems a bit odd to me but hey, what do I know. I use a computer, a microphone and an impulse testing program to adjust the speakers in time, phase and frequency response. This does not negate the use of appropriate acoustic treatments and intelligent speaker location. I adhere to the symmetry concept and designed my media room accordingly. But, having measured quite a few speakers this does not guarantee the best imaging or symmetrical performance. Even the best manufacturers are not capable of making two speakers perform exactly the same. There are always some differences in frequency response. This is were a room control system comes into play. It can make both channels virtually identical which results in the best imaging.