I can't handle ZM62 @ 23lbs, so I doubt 30lbs will be an improvement! I do find tension a bizarre thing though. I can't hack ZM62 @ 23lbs, but I love BG66U @ 26 or 27lbs. VS850 I've only ever tried at 24/25/26lbs and I feel like I could easily go higher without too much issue. I've opted for ZM67 though on all my sample and prototype rackets simply because of its tension holding ability. It was a close run race though vs VS850.