Have done a number of searches on Talk Tennis and read through the customer feedback and TW review (and video) posted. Not really that much buzz either way on this one. The TW review was mixed and maybe the 400 Tour did a bit better. The customer feeback seems very solid. I played and owned both the AG and the 4D sersions. The new Bio Tour seems much less stiff and powerful from specs and reports.. even underpowered??. The other 500 Tours never could be said to be a control frame. Any thoughts.. loved it.. hated it??? Thanks..