i break 2 string sets a week using poly. i played a match once where i broke all three of my identical frame racquets and had to borrow a racquet from the stands. i lost. you should never need two different racquets during matches. any variation in weight and balance will make your swing different thus making u hit the ball differently. find the racquet that does what you want and stick with it. but remember ull never get the perfect racquet. i wanted something will serve power, but controll on groundstrokes. i had to compromise a little on both to find a nice balance.