I need your help! I love my Dunlop Aerogel 4D 500 Tour but the stiffness of that frame (71) is killing my elbow/shoulder. I want to exchange it for the much more flexible 300 (60 flex rating) but I am concerned about the advertized low power level of the 300. Tennis.com has it rated at a 1853 power rating, which is extremely low....even lower than a Head Prestige. The salesman tells me the 300 is just a little lower than the 500. Who is right? I can handle a small dropoff on power, but not a huge one. Thanks!