Stringreen, I am basically agreeing with you about the value of correcting azimuth. On the subject of the Foz and its wonderfulness, I am not qualified, because I do not own one, and I do not fully understand how it works. I do know however, that there have been some complaints about it. One possible problem I recall was a claim that it becomes inaccurate if there is even slight decay of the voltage coming from the battery. That didn't quite make sense to me (because integrated circuits such as the ones that must be used in the Foz will generally work fine so long as the power voltage is approximately Ok), but that's what more than one person was claiming.
"Straight" talk
I can't emphasize enough about the importance of proper azimuth. When even a bit off, the result is smearing of soundstage, emphasis of one channel or the other, blurring of lyrics, loss or air around the instruments...etc. If Paul Simon (et al) doesn't sing in his own space exactly between your speakers....better get a Foz.