I’m very interested in the new iso driver. Most critical reviews I think have to do with shaft selection. I’d prefer a Maltby shaft or similar, but if I’m reading correctly most players are having success with a higher priced shaft. Was there testing done with a Maltby shaft? I’m not concerned with a smaller sweet spot. Anybody want to chime in with what shaft there playing in this head. The correct combo reviews indicate ‘awesome’, others are having some difficulty.  Thanks in advance.