I usually have 2 of the same frames in my bag at the same time for matches. (I'd love to afford 3 or 4; wouldn't we all) I prefer to play one until the string breaks then start using the second. I was playing against a guy last weekend that every set switches between his 2 racquets. He said that way they feel very similar. I don't like that because when one racquet has it's strings break, the other is probably very close. Besides, a few pounds of tension loss is that big of a difference in my 4.0 world. What do you guys do?