Switched during a match
I remember watching Agassi in a televised match (forgot which tournament, but it was a year or more ago, maybe three) and when he switched racquets we were informed by the TV commentator that Agassi had switched to a racquet with a smaller head size. Apparently, he wasn't producing the shots he wanted with the larger head size racquet. This suggests to me that he is prepared to hit with a smaller head size racquet depending on the weather (wind) and court conditions and what his opponent may or may not be doing. The racquets looked identical except for head size. Though I don't remebmer the details (which tournament, etc.), I remember this with certainty. Of course the commentator could have been mistaken. Though the racquet looked smaller to me, could have been the power of suggestion.