I tried the BLX90 demo in RPM17 @ 45lbs. It's pretty hard as a string, which is why I dropped it from my 48-53lbs using Luxilon Alu BB using the K90. It plays well enough, with ample spin and power, but it felt less punchy and loses bite after the 3rd day. I used it for 6 days and it played well. Just for myself, a 5.0-5.5 (depending on the day ) all courter, the racquet is just a bit too dead with the BLX AND RPM, robbing it of a bit of feel I like at the net. Off the ground and the serve, the combo is good, giving me a balance of spin and power. I normally use RPM mains with gut cross, 35-40lbs mains, 40-46lbs cross.