Yep, it's legal. I knew an old guy that played 4.5+ doubles with a POG SOS (super OS) with a string pattern similar to this @~30 lbs. He actually had a ball go through the string bed on a particularly well struck ball...
@LAL: good question... I'd err towards towards removing the bottom... I strike the ball closer to that area less.
4x Dunlop Bio 200 L // Babolat Sensor
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