i think the problem is it is always a compromise... if you think your speakers are lacking in low bass and you move them closer to the wall to compensate then you may find that the low bass increses. however, the upper and mid bass (which were fine before) may also increase.
also, if you move the speakers closer to the rear wall, your depth of soundstage will obviously become limited. i think it also stands to reason that if you move the speakers closer to the side walls (and hence the reflection points) you will notice an increase in treble. just my thoughts though
as grimley noted it is best to work on trial and error to find the optimal position for your speakers. failing that try fiddling with the stands, what you use between speakers and stands, foam bungs etc to acheive the best from your speakers - though judging by your recent spate of speaker related topics i think you have exhausted all other options?