Don, I would have to disagree that "cranking the guitar up and down isn't good for it". Many luthiers advocate just such a practice, especially when the guitar is new. (I am talking about lowering the tuning a quarter tone down from concert)

Admittedly it is all, by necessity, pretty subjective, whatever opinion one holds as to the merits or demerits of such a practice, (unless somebody has carried out a controlled experiment of which I am unaware).

It does seem to me that allowing the soundboard to vibrate at frequencies it would not normally experience could only be beneficial as far as allowing it to "open up" is concerned.

Murray